Climate Change Blogs

Carbon Dioxide and Climate: What We Knew Then, What We Know Now

Published: September 22, 2015
We’re in the midst of a landmark period for our changing climate: the warmest year thus far in the warmest decade in global records of surface air temperature. This is also a crucial time for dialogue on climate change, as we approach a major UN meeting in Paris this December. At that meeting, delegates from around the world will try valiantly to hammer out the first entirely new global agreement in 17 years for reducing greenhouse-gas emissions. We can expect a steady drumbeat of events building up to Paris. This week, Pope Francis is expected to bring his extraordinary message on climate change to the halls of Congress in an address on Wednesday, with a massive rally for climate action scheduled for Washington, D.C., that same day. The pope then heads to New York for a Thursday address at the United Nations, where more than 150 world leaders at a summit on sustainable development are set to adopt 17 ambitious goals, one of which is “take urgent action to confront climate change and its impacts.”

Motivating all this activity is the inexorable build-up of carbon dioxide and other greenhouse gases in our global atmosphere as a result of burning fossil fuels (coal, oil, and gas). When fossil fuels are burned, carbon from the fuel joins with an oxygen molecule from the air to create CO2. Because carbon dioxide is odorless and invisible, it’s all too easy to ignore. People had a harder time ignoring the “emissions” when our land-based transportation was conducted by horse-drawn wagon!

Despite its literal invisibility, carbon dioxide is all too real a substance, and fossil fuels add a tremendous amount of it to our atmosphere. Figure 1 shows how global CO2 emissions have unfolded over the last forty-plus years (up through 2013, the most recent year with complete data). The graphic, created by WU’s Jerimiah Brown using data from the Netherlands Environmental Assessment Agency, tells us much about the situation leading to the upcoming talks in Paris.

Figure 1. Annual emissions of the greenhouse gas carbon dioxide produced by fossil fuel use and cement manufacture over the period 1970 - 2015. Cement production is only a small portion of this total, now around 5% annually. Image credit: Jerimiah Brown, Weather Underground, using data from the Netherlands Environmental Assessment Agency. Here is a high-resolution PDF version of the graphic.

A few things jump out from Figure 1:

--Global emissions are still climbing. In the year 2013, fossil fuel use and cement production put an estimated 35.3 billion metric tons of CO2 into the air (a metric ton is about 10% greater than a U.S. ton). That’s more than twice the amount emitted in 1970. Cement production is only a sliver of this total--historically about 2-3%, but now closer to 5%. Roughly 46% of the annual emissions shown in the graphic remain in the atmosphere each year, with the rest absorbed fairly promptly by oceans and land areas. As evident on the bottom half of Figure 1, emissions can drop slightly from one year to the next, as they did during the recessions of the early 1980s, early 1990s, and late 2000s. However, each recovery has led the way to still-higher global CO2 emissions. And even when the emissions do drop slightly in a given year, carbon dioxide continues to build up in the atmosphere, just as your credit-card balance goes up even when you cut back on how much you put on your card. This is why the amount of CO2 in the global atmosphere has increased every year since regular measurements began in 1958.

--Nation by nation, the United States no longer leads the pack. Back in the late 1990s, the U.S. was responsible for about 30% of global CO2 emissions, while China represented about 15%. Now the roles have switched as a result of China’s breakneck pace in manufacturing and development. In 2013, China was responsible for roughly 29% of global CO2 emissions, with the U.S. at around 15%. A substantial part of China’s CO2 emissions is the result of items being manufactured for sale in the United States and elsewhere; here’s a very helpful analysis from Carbon Brief on how this affects the global picture.

--Per capita, the U.S. is still in the driver’s seat. Because the United States has less than a quarter of China’s population, the amount of CO2 emitted per person is more than twice as much in the U.S. versus China. A few oil-producing nations in the Middle East have even higher per-capita rates, but their small populations means that they produce far less CO2 overall than the United States.

--Decades of emissions add up. When the atmosphere's stock of carbon dioxide goes up, it takes several hundred years for the oceans to absorb about 75 percent of this excess. The remaining 25 percent or so is stuck in the atmosphere for much longer--some of it for more than 100,000 years. This is why emissions from decades ago still have a big impact on climate. The list at upper left of Figure 1 shows the cumulative emissions from six top emitters, plus the 28 nations that now make up the European Union (EU28). Of the total amount of CO2 put into the air from 1970 to 2013, the US is responsible for about 22%; the EU28, about 18%; and China, about 15%. If you go back before 1970, the United States has an even larger share of the pie.

--Progress is possible. As a group, the EU28 nations are now emitting about 14% less CO2 than they were in 1990. That’s noteworthy when you consider that the EU28’s population and level of development is roughly comparable to the United States’. Back in the early 1980s, the US and EU28 had nearly identical CO2 emissions. By 2013, the US annual total was about 43% more than the EU28’s.

Commentary: what it means for the Paris talks

Whatever emerges in Paris is likely to be much different than the only global-scale agreement to date on carbon emissions: the Kyoto Protocol. Created in 1998, Kyoto was hamstrung by understandable tension between developed countries (the U.S. in particular) and developing nations (especially China and India). Many participants from around the globe felt it was unfair to restrict the right of less-prosperous countries to use fossil fuel to grow their economies after rich nations had had virtually unlimited access to it. The resulting agreement largely held back from emission restrictions for the developing world--and in response, the U.S. Congress voted 98-0 not to ratify Kyoto. The upshot is that most of the world’s economic activity since 1998 has taken place outside the bounds of the protocol, leaving the door wide open for huge global increases in CO2 emissions. Meanwhile, the European Union did even better than its Kyoto pledge, cutting its emissions of the top greenhouse gases 18% below 1990 levels by 2012.

Given the trends in Figure 1, a Kyoto-style approach clearly won’t work this time around. Any global agreement on emissions needs to include both the United States and China, as well as fast-growing India, in order to be effective. Yet it’s hard to imagine the current U.S. Congress agreeing to any globally constructed emissions cuts. Given this constraint and others, a new strategy has taken shape: each nation is coming up with its own nonbinding “pledges,” which will be enforced largely through peer pressure and perhaps eventually through economic tools such as tariffs and sanctions. An unprecedented agreement between China and the United States late in 2014 led to pledges by China to maximize its greenhouse gas emissions no later than 2030 (though this would still allow China’s total emissions to increase for more than a decade) and by the U.S. to reduce its emissions 12-19% below 1990 levels by 2025 (including emissions related to land use and forestry, which complicates the picture somewhat). Earlier this month, a group of some of the largest cities of China and the United States agreed on emission targets that in some cases are even more ambitious than the national goals.

Historic as they are, these examples above show how a patchwork of nation-by-nation agreements may end up resembling a crazy quilt. The big question facing delegates to Paris is whether such a global set of voluntary emission cuts, even if they’re adhered to, will be enough. There’s no single bright line that separates a livable climate from one riddled by disaster, but for more than 15 years, many scientists and policymakers have worked toward the commonly cited goal of no more than a 2°C global temperature rise above pre-industrial levels. In June, an analysis by the International Energy Agency showed that the combined global pledges thus far would allow a temperature rise of 2.6°C by 2100 and 3.5°C in the 2200s. Such a rise would boost the odds of irreversible physical change, such as the unstoppable melting of ice sheets. It would also raise the risk of truly serious impacts on agriculture, water and food supply, and human health, raising the specter of increased conflict and climate refugees. Some analysts are already pointing to the role of record drought in Syria as a major factor in that nation's civil war and the subsequent flood of migrants. "News reports calling the refugees the first 'climate refugees' are getting too far ahead of the curve," asserted Andrew Freedman in Mashable. "But the ongoing humanitarian disaster provides a teaching opportunity for a time not too long from now when the first true climate refugees trigger a similar situation."

New discoveries of oil, coal, and gas in recent years have led to unexpectedly abundant supplies of fossil fuel. Yet if we want to be fairly confident of avoiding the 2°C benchmark, we can only burn a small fraction of this fossil fuel--only about 20%, according to one influential estimate that was reinforced by the IPCC in 2013. Any global agreement that keeps us near the 2°C goal will indirectly force the vast majority of the world’s proven oil, coal, and gas reserves to remain in the ground. Ultimately, this would be a conservative action in the truest sense--conserving fossil fuel--but some of the world’s largest and most powerful corporations would stand to lose trillions of dollars in value if this played out. We know that at least one major firm had some sense of the dilemma more than 30 years ago. An major investigative report by Inside Climate News, now being published as a multipart series, describes how Exxon carried out extensive observational and computational research, starting as far back as the 1970s, that pointed to the huge risks posed by increasing carbon dioxide.

We now know that massive amounts of energy can be produced apart from fossil fuels, with the costs steadily dropping. A group of eminent British scientists and policy leaders has called for a Global Apollo Program--an international 10-year R&D effort to make renewable energy more affordable than fossil fuel. Such efforts will go a long way toward giving any global agreement cobbled together in Paris a fighting chance to succeed.

Dr. Ricky Rood is attending a Climate Data Summit sponsored by the Risky Business project as part of Climate Week NYC. See his WU blog post from September 19 for more about the long and very winding road to the negotiations in Paris. My post with Jeff Masters from earlier today outlines current happenings in the tropics; we'll be back with more on Wednesday.

Bob Henson

El Niño and California Drought: Simplistically

Published: September 9, 2015
El Niño and California Drought: Simplistically

Well, I was surprised to wake up Sunday to El Niño, nicknamed Bruce Lee, could mean nasty Colorado snows. I was just getting it together to prepare for Godzilla El Niño. Now I have some hybrid, flirty, mixed martial arts monster to prepare for. Must say I was, also, surprised to see Bruce Lee attributed to our friends at (Revision: See the end of this new entry) It did lead to a relevation; we are headed back to polytheism. Aeolus blew a wind, out here, it is called Maria(h) and, well, here in 2015, in the Northwest U.S., there has not been a lot of Tess, and without Tess, Joe has just gone crazy. Apollo’s chariot descends towards the west, and I still have a blog to write before Selene awakes.

With this, the challenges offered to me by my new phone, and the stunning complexity of the “radio” in my rental car last week, there is not much place left for me in the world.

This is my El Niño blog. El Niño and La Niña are names given to frequently occurring patterns of variation that are concentrated in the tropical Pacific Ocean, but that change the average temperature of Earth for about a year. When there is an El Niño the globe is warmer, and when there is a La Niña the globe is cooler.

At this point, all of the forecast centers (see list at the end), are documenting and forecasting a “strong” El Niño event (Nature news story on 2015 El Niño). The current El Niño is comparable in strength to the strong El Niño of 1997-98, which for the U.S according to Ross et al. (1998), “was marked by a record breaking El Nino event and unusual extremes in parts of the country. Overall, the winter (December 1997- February 1998) was the second warmest and seventh wettest since 1895. Severe weather events included flooding in the southeast, an ice storm in the northeast, flooding in California, and tornadoes in Florida. The winter was dominated by an El Niño-influenced weather pattern, with wetter than normal conditions across much of the southern third of the country and warmer than normal conditions across much of the northern two-thirds of the country.”

There have been many blogs and stories about how this El Niño is the same or different from 1997-98. A notable analysis which begat many of the other stories comes from Andrea Thompson at Climate Central, who used several quotes from Michele L’Heureux at the National Oceanic and Atmospheric Administration. Quoting the Climate Central article

“On the one hand, the two are comparable given that 1997 was the strongest El Niño on record and, at the moment, the best science indicates that the current event could match or rival that one — at least in terms of ocean temperatures. But on the other hand, each El Niño event is its own beast, the product of conditions in the ocean and atmosphere, of climate and weather that are unique in that particular place and time.

In the, albeit very short, modern record of El Niños, “we cannot find a single El Niño event that tracked like another El Niño event,” Michelle L’Heureux, a forecaster with NOAA’s Climate Prediction Center, said.

Forecasters like L’Heureux cringe at comparisons because there’s no guarantee the impacts of one El Niño will be just like that of a previous one, even if they look broadly similar. And it’s those impacts — like potential rains in drought-stricken California — that most really care about.”

What do I have to contribute to this discussion? Well, I am partial to this link from BBC News in November, 1997 – Science struggling to predict El Niño devastation. (Scientists had yet to find the language of hybrid, flirty, mixed martial arts monsters.) So I am going to offer up my simplistic thinking about El Niño.

The MetOffice has in their Weather for kids section an article on Understanding Weather. There is a small section on El Niño, which says, “The tropical Pacific Ocean has a warming and cooling cycle. This cycle is a completely natural event and usually lasts between three to seven years.” There is a nice figure:

Figure 1: From the MetOffice. La Niña effects weather all over the globe. During La Niña it is cool in the eastern Pacific. To the west of the cool area, marked La Niña, the water is warm, and there is active weather, represented by the clouds. Related to this region of active weather, are impacts throughout the northern hemisphere. For this plot, focused on the MetOffice’s priority area in Britain, the influence is represented by the red arrows, showing an impact over Europe.

I like the figure because it is simple. Unfortunately, it is for La Niña, the time when it is cool in the eastern Pacific, as opposed to El Niño, when the eastern Pacific is warm. However, it illustrates the point that the region of active weather has influence throughout the hemisphere. That is, that region stands as a place where weather systems can get started, pick up water, and then move to the north and the east. These weather systems move preferentially in paths that cross broad geographical regions, perhaps, a little less focused than suggested in this figure.

I am going to try a comparison here. Imagine that you need to walk across a thick forest, perhaps a wilderness, from west to east. You have some device that allows you to know that you are walking from west to east. But there are no major cleared paths in the forest. If a bunch of people started out together on one side of the forest, they can find their way through the forest, perhaps, all by different paths. And when they get to the other side, the bunch of people is likely to be spread out, because the paths diverged. Still, they made it from west to east.

One of the most fundamental facts of weather and climate is that the Sun provides more energy in the Earth’s tropics, near the Equator, than at the poles. The atmosphere and oceans respond to this imbalance of energy by trying to even it out. Therefore, weather systems transport heat (and water) from the equator towards the poles. Another fundamental fact is that the rotation of the Earth causes weather patterns to move from west to east. The location of oceans and continents and mountains on the continents, means that there are preferential paths that weather systems follow. They might start as a bunch in the tropics, but by the time they have made it through to the poles they have spread out.

What happens during El Niño, the eastern Pacific becomes warmer, and those little clouds in Figure 1 in the western Pacific Ocean move over to the east. That is, the region of active weather that helps to determine the start of the paths of weather systems moves. Weather systems still have to move north towards the pole and to the east, aligning with the rotation of the Earth.

So taking the lead from Figure 1, I have an even more simplistic figure. In Figure 2, all I suggest is that the paths of influence move eastward and, therefore, have a more direct influence on North America. With high confidence, we can say that storminess and moisture will increase somewhere in western North America. However, which particular path or paths that will be present in a specific year is far more difficult to predict in advance. For any given year, the global pattern might set up so that there is a path that leads to a series of storms. In the 1997-98 El Niño, California received a lot of rain. My figure suggests that California is likely to receive more rain than in a non - El Niño year; however, it is not a certain bet.

Figure 2: El Niño effects weather all over the globe. During El Niño it is warm in the eastern Pacific, and there is active weather, represented by the clouds. Related to this region of active weather, are impacts throughout the northern hemisphere. For this plot, focused on western North America, the influence is represented by the arrows. The arrows suggest several paths of influence are expected. The background map is from Ed Wiebe at UVic Climate Lab.

Above, I cited an article that emphasized that no two El Niño events are alike. Continuing with my simplistic approach, Figure 3 emphasizes two significant differences between now and 1997-98. First, we have that area of warm water off of the coast in the Northeast Pacific, which has been cited in other studies as having a large influence on North American weather. Second, we have the tremendous changes in the Arctic. Both of these are sources of uncertainty that are not simplistically evaluated based on past experience; hence, the question marks in the figure. These features should be expected to alter the paths of weather systems (storms) because they change the contrast between warm and cool regions; hence, change the energy transport. They are also likely to change the character of the storms in the sense of providing easy moisture to the atmosphere. Model experiments could be designed to assist in thinking about these uncertainties, but I am not aware of any systematic approach to do this.

Figure 3: Same as Figure 2, but with warm areas in Northeast Pacific and the Arctic to highlight differences with previous El Niño events. The background map is from Ed Wiebe at UVic Climate Lab.

What I have presented here is simplistic, and focused primarily on western North America, where there is persistent and dangerous drought. There is a lot of attention in the U.S. media on the influence El Niño will have on the drought. The simplistic thinking that El Niño brings a lot of rain in California is challenged not only by the inherent variability of weather and climate, but also by the persistent warm area in the Northeast Pacific and by the changes in the Arctic. The Arctic changes are undeniably related to planetary warming, and they represent a change that should be presumed to have influence on the movement of weather systems.

I end with another link to the MetOffice, Extreme weather planning for financial services. In this document, it is pointed out that recognizable patterns of risk and benefit are associated with El Niño and La Niña. This allows the use of knowledge to prepare a portfolio of responses that can be implemented as the specifics of the 2015-16 El Niño are revealed and short-term (weather) forecasts become accurate.


Forecast and Analysis Centers

Climate Prediction Center Alert System and the Climate Prediction Center Diagnostic Discussion

International Research Institute Forecast Products and the Quick Look

Japanese Meteorological Agency El Niño Monitoring and Outlook and a nice graph of historical events

Australian Bureau of Meteorology Wrapup

Information Portals

CLIVAR (Variability and predictability of the ocean-atmosphere system) Forecast Page

World Meteorological Updates

Pacific Marine Environmental Laboratory El Niño Theme Page Forecasts

Climate Prediction Center FAQ

NOAA’s El Niño Page and NOAA’s La Niña Page

Summaries in Blogs


Figure 3: Ortelius World Map with a Monster in the Eastern Pacific. From Wikipedia

Arctic Sea Ice May Reach Second-Lowest Extent on Record This Month

Published: September 3, 2015
A burst of late-season loss over the last several weeks has put the Arctic Ocean’s ice cover within reach of the lowest extent observed in any year except 2012. The extent values tracked by the National Snow and Ice Data Center, or NSIDC (see Figure 1), show that 2015 has caught up to several other recent years in the amount of ice depleted, and is poised to surpass 2011 and 2007 if the rapid loss continues. The milestone is a timely one, given this week’s historic Alaskan visit by President Barack Obama.

NSIDC reviewed the near-term outlook for sea ice in an update posted on Wednesday: “There is still a possibility that 2015 extent will be lower than 4.3 million square kilometers, the third lowest sea ice extent, surpassing the 2011 sea ice extent minimum, and a small chance of surpassing 2007, resulting in the second-lowest daily minimum. This assumes that we continue to have sea ice loss rates at least as fast as those of 2010. This was indeed the case for the final ten days of August 2015.”

As explained by NSIDC with a swiss-cheese analogy, sea ice extent refers to the amount of ocean covered by at least 15 percent ice concentration (the dimensions of the slice of cheese), whereas sea ice area is the literal amount of ocean covered by ice, not counting the holes. Arctic ice normally reaches its maximum extent in March and its minimum in September. The ice extent drops in spring and summer largely as a result of melting (from below and above), though it can also be influenced by compaction (which pushes broken-up areas of ice together, reducing the total ice extent). Another factor is a pattern of atmospheric pressure called the Arctic Dipole, which favors Asia-to-Europe cross-polar flow that can push ice out the Fram Strait into the North Atlantic, hastening ice depletion.

Figure 1. Sea ice extent across the Arctic Ocean for the period August-November, 1979-2015. This year’s extent was just over 4.6 million square kilometers on September 2, and dropping rapidly, with only the 2012 curve falling much lower. Nine of the 10 lowest extent values have occurred within the last decade. Image credit: NSIDC.

There’s still plenty of darkness and cold air to foster ice-cover regrowth across most of the Arctic each winter, but the summer minima have plummeted in recent decades (see Figure 1). With just weeks left before net ice expansion resumes, it’s all but impossible for 2015 to catch up to 2012. That year saw the lowest extent since satellite records began in 1979 (3.41 million square km, or about 50% below the typical minimum observed in the 1980s and 1990s). However, a minimum in the vicinity of 4.2 to 4.3 million sq km seems within reach. That would be well below the average value of 4.8 million sq km predicted by an array of 38 participants in the latest monthly Sea Ice Outlook produced by the Sea Ice Prediction Network. By that time this forecast was issued (August 20), Arctic ice extent had come off near record-low values for late spring, recovered somewhat by early summer—thanks in part to a cold June across the Arctic, with relatively little melting--and dipped again in August, with fairly steady losses through the month. Then came a surprisingly strong cyclone that developed across the Beaufort Sea last week. High winds and seas from that storm helped weaken a large arm of multi-year ice extending from the central Arctic into the Beaufort Sea. The storm also brought punishing waves and erosion to the Alaskan coast near Barrow (see Figure 2).

Figure 2. High surf batters the coast near downtown Barrow, Alaska, on August 27, 2015. Image source: Barrow Sea Ice Webcam, tweeted by Brian Brettschneider

Figure 3. This intense surface cyclone disrupted a large chunk of Arctic sea ice that extended from the Central Arctic into the Beaufort Sea. Analysis for 0000 GMT on August 27, 2015, shows sea level pressure (in green); potential temperature at the tropopause, a marker of upper-level energy that can help foster surface cyclones (in black); and the extent of Arctic sea ice (grey shading, with concentration fraction shown by the bar at right). A corresponding animation shows the sequence of events beginning on August 16 and segues into a model prediction from August 2 to September 9. Image credit: Steven Cavallo, University of Oklahoma.

What’s ahead this month and beyond?
“It is still pretty stormy over the Arctic,” said Steven Cavallo, a University of Oklahoma meteorologist who specializes in polar weather. Cavallo has researched tropopause polar vortices (TPVs) and their relationship to surface cyclones. “There are a lot of TPVs around, meaning the potential for surface cyclone formation is high, so I think the forecast sensitivity is very high right now and there could still be some significant ice loss.” Recent model runs have flip-flopped in predicting additional strong cyclones over the Arctic over the next few days. Cavallo hypothesizes this could be related to the difficult-to-predict effects of tropical cyclones recurving into the polar jet stream. At the Arctic Sea Ice Blog and Forum, there’s been a lot of conversation along these lines. “People on the forum are speculating on and off about a 'train' of cyclones, either Atlantic or Pacific, injecting heat and moisture into the Arctic,” said blog/forum founder Neven Acropolis in an email. Two good places to follow the dialogue are “The 2015 melting season” thread and Acropolis’s own excellent posts.

Figure 4. Sea ice concentration for September 1, 2015, as calculated by the National Snow and Ice Data Center. Areas shaded in lighter blue denote reduced concentration (area) within the overall bounds of ice extent. Image credit: NSIDC.

The ice that’s managing to persist across the Arctic this summer doesn’t look especially healthy. Polar climate specialist Jennifer Francis (Rutgers University) calls out the warning signs conveyed in the most recent ice concentration image from NSIDC (see Figure 4, at right). “Much of the ice that's left is either slushy, severely broken up, or covered in melt ponds,” Francis noted. Depletion is especially large on the Pacific side of the Arctic, she added, which recent work suggests may favor a severe winter in parts of eastern North America. Much research in the last few years by Francis and others has worked to draw connections between Arctic sea ice loss, high-latitude warming, and midlatitude winter weather. A new entry in this mini-discipline is a paper published last week in Nature Geoscience that links two modes of warm Arctic weather to subsequent winter cold downstream across East Asia and North America.

The power of this year’s still-strengthening El Niño event may be enough to swamp whatever influence the decline of Arctic sea ice might have on the upcoming winter across North America. Sea-surface temperatures (SSTs) are cooling over the western tropical Pacific in tandem with the building El Niño warmth over the eastern tropical Pacific. A number of studies (nicely summarized by Daniel Swain at California Weather Blog) suggest that the western-Pacific cooling will help lead to more storminess over the Gulf of Alaska, which in turn could finally erode the persistently warm SSTs and the “ridiculously resilient ridge” of high pressure that have prevailed in that area for most of the last two years. If so, a pathway will be carved for the classic El Niño signature of very mild winter temperatures across most of Canada and the northern United States, in line with the latest seasonal forecasts from NOAA. If, instead, we see a third consecutive winter of unusual cold across the U.S. Midwest and Northeast, it’ll be a strong sign that another player is onstage. Judah Cohen (Atmospheric and Environmental Research) bases his North American winter forecasts in part on the apparent relationship between low Arctic sea ice extent and cold Northern Hemisphere winters. “I really do think that this could be a very interesting winter and could be very informative on the interplay of tropical vs. Arctic forcing,” said Cohen in an email. “Can the Arctic, as a forcing agent of mid-latitude weather, finally step out out of the shadow of the tropics or not?”

Figure 5. Both the Arctic and Antarctic rack up more than 12 million square klilometers of sea ice extent each winter, but the summer ice depletion is greater in the Antarctic, where the ice sits at lower latitudes. Image credit: The Cryosphere Today/University of Illinois at Urbana-Champaign.

Why it matters
Although a coating of ice does return to most of the Arctic Ocean each winter, the persistence of ice through the summer is a vital part of the region’s ecosystem. Polar bears, ringed seals, and other wildlife use the ice as a platform for hunting prey and raising their young. Many indigenous residents of the lands circling the Arctic have also relied on the presence of year-round ice for centuries. The picture is far different at the other end of the world: instead of being surrounded by ocean, the South Pole lies at the heart of the landmass of Antarctica. Sea ice in this hemisphere develops on the fringes of Antarctica, which puts it at a lower latitude than most Arctic sea ice. As a result, nearly all of the ice that forms each winter around Antarctica melts back each summer. The average wintertime extent of ice around Antarctica has actually grown slightly in recent years, for reasons not fully understood. This is often falsely presented as “balancing” the loss of Arctic sea ice, but the Arctic loss is far more substantial than the Antarctic gain, and much more important to regional climate, ecology, and economy. Ice-free navigation is now once again possible in the Arctic along the coast of Canada (the southern route of the fabled Northwest Passage), and has been open for over a month along the coast of Russia (the Northeast Passage or Northern Sea Route.) Mariners have been attempting to sail these passages since 1497; the first time they were open for ice-free navigation without an icebreaker was in 2005 for the Northeast Passage and 2007 for the Northwest Passage. The continuing erosion of summer ice cover in the Arctic has stoked interest in expanding industrial activity across the region, including oil and gas development--an ironic turn of events, given the role of fossil-fuel-produced greenhouse gases in the worldwide warming of recent decades.

Tropical Atlantic: Tenacious Fred hangs on
Tropical Storm Fred has been in “never say die” mode, hanging on as a minimal tropical storm on Thursday morning as it drifted across the eastern Atlantic. New thunderstorms blossomed on the east side of Fred’s circulation center on Wednesday night into Thursday, despite stout wind shear of more than 35 mph. By midday Thursday, only a much smaller patch of convection was located just north of Fred’s exposed center. The shear is expected to increase, and the National Hurricane Center expects Fred to become a remnant low by Friday. NHC is mentioning the possibility, though, that Fred could spring back to life in five days, when the storm will encounter lower wind shear and anomalously warm waters of 27.5°C (82°F) over 500 miles southwest of the Azores Islands.

New tropical wave moving off the coast of Africa has potential to develop
A strong tropical wave with plenty of spin and heavy thunderstorm activity will move off the coast of Africa by Thursday night, and has the potential to become a tropical depression early next week as the storm moves west at 15 - 20 mph. The 00Z Thursday (8 pm EDT Wednesday) runs of two of our top three models for predicting tropical cyclone genesis, the GFS and European models, predicted that this new wave would become a tropical depression in the waters southwest of the Cape Verde islands by Monday. In their 8 am EDT Thursday Tropical Weather Outlook, NHC gave the wave 2-day and 5-day odds of development of 10% and 40%, respectively. The tropical Atlantic is relatively moist, has the highest sea surface temperatures of the year, and is expected to have low to moderate wind shear, conditions which favor development. The wave should take about 7 - 8 days to make it to the Lesser Antilles Islands.

Figure 6.Typhoon Kilo and Hurricanes Ignacio and Jimena, all captured in this infrared image from the GOES-West satellite at 1330 GMT (9:30 am) Thursday, September 3, 2015. Image credit: NOAA/NHC and Michael Lowry, The Weather Channel.

Pacific continues to bristle with tropical cyclones
The Northeast Pacific has a new named system, Tropical Storm Kevin. As of 11 am EDT Thursday, Kevin’s top sustained winds had increased to 50 mph. Kevin is expected to live out the rest of its life below hurricane strength over open water before increasing amounts of shear and mid-level dry air take their toll. Some moisture associated with Kevin will be working its way into Colorado and New Mexico through Saturday ahead of a large upper-level trough approaching the region, enhancing shower and thunderstorm activity there. In the Central Pacific, powerful Hurricane Jimena is very slowly weakening but remains a high-end Category 2 as it embarks on a broad cyclonic loop well northeast of Hawaii over the next few days. We’ll have to keep an eye on Jimena in the long range, as the recent runs of the GFS and European models bring Jimena back toward Hawaii from the northeast late next week, still as a tropical storm. Such a scenario might be dismissed out of hand in any other year, but with SSTs so warm in the Central and Northeast Pacific, Jimena could conceivably remain over waters at or above the threshold of 26°C (79°F) over most or all of such a trek. Meanwhile, Hurricane Ignacio, now a Category 1 storm north of Hawaii, is also weakening but remains impressively well-structured, with extensive spiral banding. Ignacio is on track to plow into the Gulf of Alaska as a powerful extratropical storm by early next week. En route, Ignacio will pass over unusually warm waters along the way, with sea-surface temperatures up to 3-4°C (5.4-7.2°F) above average (though eventually too cool to support Ignacio as a tropical cyclone).

Ultra-resilient Typhoon Kilo is now in its 14th day as a tropical cyclone, including a long spell as a major hurricane. Kilo is predicted to steadily reintensify over the next 3-4 days, again reaching Category 4 strength by Tuesday as it moves on a westward loop that will likely take it several hundred miles north of Wake Island. In the long range, Kilo may pose a threat to Japan.

We’ll be back with our next update on Friday.

Bob Henson and Jeff Masters

U.S. Wildfires 2015: Are The Worst Yet To Come?

Published: September 2, 2015
Thus far, 2015 has been one of the worst U.S. wildland fire seasons since modern records began. More than 8.2 million acres have burned across the nation as of September 1, an area larger than Massachusetts and Rhode Island combined. Across the last ten years, that’s the largest amount of fire-scorched U.S. acreage for the January-August period, and it’s close to 50% above the decadal year-to-date average. We are well ahead of the pace set in 2007, when 9,328,045 acres burned, the highest annual total in records going back to 1960.

Figure 1. Flames from a backfire operation burn behind an emergency vehicle near the Rocky Fire on August 3, 2015, near Clearlake, California, north of San Francisco. Some 3,000 firefighters battled the Rocky Fire, which burned more than 80,000 acres and destroyed almost 100 residences and outbuildings. Image credit: Justin Sullivan/Getty images.

There’s a more complex story hiding behind these factoids. Certainly there have been some intense and large fires across the Pacific Northwest, pumping out smoke that’s reddened skies and clotted lungs across large swaths of the nation. But up until August, the main factor behind this year’s large wildfire acreage (as explained by Tom Yulsman at Discover’s ImaGeo blog) was the extent of fire in Alaska. More than 5.1 million acres had burned across the state as of September 1, most of it by midsummer. With Alaska’s fire activity now slowing down, the state’s total affected acreage will likely rank second behind 2004, when a total of 6,590,140 Alaskan acres went up in flames.

It was clear by early summer that the Pacific Northwest was in line for a potentially rough fire season, with long streches of record spring and summer heat following a winter with record-low snowpack. Simply having a parched landscape doesn’t automatically translate into big fire, though. If strong, dry winds are absent; if fires aren’t triggered by lightning and/or human activity; and/or if firefighters manage to tamp down fires quickly, then the potential for disaster may go unrealized. Wildfires didn’t begin taking full advantage of the Pacific Northwest’s primed-for-fire condition until mid-August, when the Okanogan Complex roared to life across north-central Washington. Now the state’s largest assemblage of wildfires on record, the Okanogan Complex (40 percent contained as of Tuedsay) has destroyed more than 170 homes.

Figure 2.The Significant Wildland Fire Potential Outlook for September 2015 shows above-normal risk across parts of four western states, as well as a small part of central Texas. Image credit: National Interagency Coordination Center.

On August 13, officials upgraded the National Preparedness Level for wildland fire to category 5, the highest, meaning that multiple major fires have the potential to exhaust all of the nation’s firefighting resources. This is the first category-5 ranking since a week-long stretch in August 2013, and the fifth such period in the last ten years. Cooler temperatures should continue to tamp down the fire risk in Alaska this month, but it’s far too soon for other western states to rest easy. The latest monthly outlooks for wildland fire potential, issued on Monday by the National Interagency Coordination Center, show an above-normal risk of significant wildfire in September across eastern Washington, northeast Oregon, and far northwest Montana, as well as the Sierra Nevada and coastal mountains south of the Bay Area in California. By October, the risk is expected to return to near normal over the Pacific Northwest and central California, but the highly populated belt of Southern California is still targeted for above-normal risk.

Why fall is the most-feared time for wildfire in California
California’s Mediterranean climate means that rainfall is focused in the period from late fall into spring, with the landscape then getting progressively drier until the next wet season kicks in. This sets up prime conditions for wildland fire during the typically warm, dry weather of September and October, sometimes goosed by strong offshore winds (dubbed the Santa Ana wind in the L.A. area). Late October 1991 brought the horrific Oakland hills firestorm, which destroyed more than 2,800 homes and killed 25 people, and Southern California’s record-setting wildfire seasons of 2003 and 2007 both peaked in October.

Figure 3. Meg Tallberg (left), whose home was not damaged by fire, offers her support to neighbor and friend Jenny Fratis (right), whose house (background) was destroyed in the Witch Fire, as residents returned to Rancho Bernardo in California's San Diego County on 25 October, 2007. Image credit: Robyn Beck/AFP/Getty Images.

This year, California is entering fire season after four years of drought, culminating in what’s been the warmest year for California in more than a century of recordkeeping. Although some unusual summer rains have provided dabs of relief across the far southeastern desert, much of the landscape across central and southern California remains tinder-dry. Some 46% of the state is now in exceptional drought, the highest ranking assigned by the National Drought Mitigation Center in its weekly U.S. Drought Monitor. That’s down a bit from 58% at this time a year ago, but the impacts of long-term drought in the hardest-hit areas remain severe. In August, a study from the University of California, Davis, estimated that the ongoing drought will cost California about $2.7 billion in 2015. Several intense, destructive fires have already struck the state, including the small but frightening, interstate-jumping North Fire east of Los Angeles in mid-July and the huge Rocky and Jerusalem Fires north of San Francisco in late July/early August.

The main questions awaiting the West’s fire-prone areas this autumn--questions that forecasters can’t answer with confidence--is how often and where windy frontal systems and/or strong offshore flow will materialize. NOAA’s seasonal outlook for September through November maintains above-average temperatures throughout the West Coast states, with precipitation below average in the Pacific Northwest and above average over southern California. The strengthening El Niño gives SoCal a good chance at above-average rains this winter, but the heaviest Niño-related rains often don't arrive till December/January.

Figure 4. While in Alaska, WU art director Lauren Moyer captured the not-so-common sight of a virtually cloud-free Mount Denali on August 3, 2015. In the foreground is a WU personal weather station, MEVCA2. Image credit: wunderphotographer moyerdestroyer.

Climate change and wildfire risk
One of the key points made by President Barack Obama in his visit to Alaska this week (including Wednesday’s scheduled stop north of the Arctic Circle, the first ever by a president in office) is the role of human-induced climate change in exacerbating wildfire risk across the state. In a speech delivered Monday in Anchorage, Obama noted: “Alaska’s fire season is now more than a month longer than it was in 1950. At one point this summer, more than 300 wildfires were burning at once.” The lengthening fire season in Alaska reflects a global trend: a new open-access analysis published in Nature Comunications in July found that 25% of Earth’s vegetated surface saw fire seasons grow longer from 1979 to 2013 by an average of close to 20%.

Figure 5. Areas that have experienced changes in the frequency of long fire weather seasons (at least one standard deviation above the historical average) during the period 1996-2013 compared with 1979–1996. Reds indicate areas where fire weather seasons have lengthened or long fire weather seasons have become more frequent. Blues indicate areas where fire weather seasons have shortened or long fire weather seasons have become less frequent. Image credit: Figure 3(b), “Climate-induced variations in global wildfire danger from 1979 to 2013,” W. Matt Jolly et al., Nature Communications 2013.

Alaska has warmed more quickly than the rest of the nation over the last 60 years, with annual average temperatures in Alaska climbing by about 3.0°F over the period from 1949 to 2014. The warming has come in phases, according to the Alaska Climate Research Center, with temperatures spiking in the 1970s and then plateauing at a “new normal” for several decades before a new level of warmth was hit in 2014, continuing into this year. The period Jan-July 2015 was Alaska’s second warmest in 91 years of recordkeeping, according to NOAA’s National Centers for Environmental Information. The U.S. National Climate Assessment, published in 2014, had this to say about Alaska’s evolving climate and fire risk: “Both wetland drying and the increased frequency of warm dry summers and associated thunderstorms have led to more large fires in the last ten years than in any decade since record-keeping began in the 1940s….More extensive and severe wildfires could shift the forests of Interior Alaska during this century from dominance by spruce to broadleaf trees for the first time in the past 4,000 to 6,000 years.”

Figure 6. Annual average temperature across Alaska, 1949 – 2014. Image credit: Alaska Climate Research Center.

Wildfires are the complex product of many variables, including forest management, fire suppression, temperatures and moisture, ignition sources, and firefighting practices. Prior to European settlement, gigantic fires were part of the natural ecosystems across much of North America. In a blog post from 2013, Andrew Revkin discusses the historical context of U.S. fire suppression and its role in helping lay the groundwork for today’s megafires. Whatever factors have led to the forests we have today, their ability to burn intensely is being stoked by rising temperatures that intensify the impacts of naturally occurring drought, a point illustrated vividly this year from California to Washington and emphasized in several recent studies (including this one, published just this week in Geophysical Research Letters). There will be some inevitable randomness in the final, fateful steps (weather events, arsonists, etc.) that lead from a particular parched landscape to a devastating fire. We’re very unlikely to see the entire West in flames anytime soon (thankfully!), but it’s reasonable to expect that heat unprecedented in modern times and dried-out vegetation will sometimes lead to fires more intense and/or widespread than ever before seen by residents of a given area. With ever-larger numbers of Americans choosing to live amid western forests, and cities such as Oakland and Los Angeles adjoining fire-prone areas, the risks to life and property will only rise with time.

Figure 7. It’s a hurricane! It’s a typhoon! It’s both! Dan Lindsey (CIRA) posted this tongue-in-cheek analysis of Kilo, using a visible image from Japan’s Himiwari-8 satellite, as the storm straddled the International Date Line on September 1, 2015. Hurricanes are reclassified as typhoons when they move west across the Date Line. The Sydney Morning News asked whether Kilo should be called a “hurriphoon” or a “typhane.” Kilo was officially reclassified from Hurricane Kilo to Typhoon Kilo at 0600 GMT on September 1. Image credit: RAMMB/CIRA/JMA.

Tropics calming down
After weeks of hyperactivity, the Northern Hemisphere tropics are beginning to calm down for the time being. The 00Z Thursday morning run of the GFS model was not predicting any new tropical cyclones to develop anywhere in the world during the next seven days, though the European model was showing possible development next week of a tropical wave expected to come off the coast of Africa this Friday. This wave is expected to move westwards at about 15 mph towards the Lesser Antilles Islands; NHC did not mention this wave in their 8 am EDT Wednesday Tropical Weather Outlook. Tropical Storm Fred continues to weaken in the far eastern North Atlantic; likewise, Hurricane Jimena in the Northeast Pacific and Hurricane Ignacio in the Central Pacific are gradually spinning down. Only Typhoon Kilo is expected to resurge over the next several days. Currently almost stationary just west of the International Date Line, Kilo should gradually accelerate westward across warm waters south of a subtropical ridge, gaining strength along the way and perhaps reaching Category 4 status once again by the end of the week. Today (September 2) is Kilo’s 13th day as a tropical cyclone, and this morning's run of the GFS model predicted that Kilo would remain a tropical cyclone for at least nine more days. According to the National Hurricane Center, the longest-lived tropical cyclone in the satellite era is Hurricane/Typhoon John, which was tracked for 31 days during August and September 1994.

WU contributor Phil Klotzbach has a new post on the recent frenzy of North Central Pacific activity; see also his two-part entry on record-setting action across the Northern Hemisphere as a whole, posted on August 25 and August 28.

We’ll be back with another post on Thursday.

Bob Henson and Jeff Masters

July 2015: Warmest Month on Record Globally

Published: August 20, 2015
The Atlantic and Pacific tropics were buzzing with activity on Thursday (see bottom of this post for a very brief update), but Thursday brought other big news as well: July 2015 was the warmest single month in 1627 months of global records that go back to January 1880, said NOAA's National Centers for Environmental Information (NCEI). The globally averaged temperature above both land and ocean surfaces was 1.46°F (0.81°C) ahead of the 20th-century average. This trumps the record for any month that was set in July 1998, surpassing that value by 0.08°F (0.14°C). On average, July is the warmest month of the year globally, tpyically driven by midsummer conditions across the Northern Hemisphere’s extensive land areas. However, according to NOAA, record warmth across much of the Pacific and Indian oceans played a major role in July’s new global record. NASA also rated July 2015 as the warmest July on record. July 2015's warmth makes the year-to-date period (January - July) the warmest such period on record, according to both NOAA and NASA. A potent El Niño event in the Eastern Pacific that crossed the threshold into the "strong" category in early July continues to intensify, and strong El Niño events release a large amount of heat to the atmosphere, typically boosting global temperatures by at least 0.1°C. This extra bump in temperature, when combined with the long-term warming of the planet due to human-caused emissions of heat-trapping gases like carbon dioxide, makes it extremely likely that 2015 will be Earth's second consecutive warmest year on record.

Figure 1. Departure of temperature from average for July 2015, the warmest single month for the globe since record keeping began in 1880. Large areas of record warmth were analyzed across many parts of the Indian and Pacific oceans, as well as in northern South America, southeast Africa, and parts of southern Europe. Image credit: National Centers for Environmental Information (NCEI) .

Global satellite-measured temperatures in July 2015 for the lowest 8 km of the atmosphere were the 10th warmest in the 37-year record, according to the University of Alabama Huntsville (UAH). The lowest 8 km of the atmosphere heats up dramatically in response to moderate to strong El Niño events, with a time lag of several months--as occurred during the El Niño events of 1998 and 2010. Thus, we should see Earth's lower atmosphere temperature hit record levels late this year and/or early in 2016.

Deadliest weather disaster of July 2015: monsoon floods in Asia
The deadliest weather-related disaster of July 2015 was flooding in Asia due to the annual monsoon, which claimed over 200 lives in Pakistan, Myanmar, Afghanistan, Bangladesh, Vietnam, India, and China. Severe flooding in these countries continued during the first ten days of August, bringing the total monsoon death toll to over 400, as reported by Bob Henson in his August 11 post.

Figure 2. Navigating a flooded area of Peshawar, Pakistan, on July 26, 2015. Torrential rains and floods in Pakistan left 36 dead and affected more than 250,000 people, disaster management officials said July 25, with swollen rivers and water channels damaging hundreds of villages. Photo credit: A Majeed/AFP/Getty Images.

Two billion-dollar weather disasters in July 2015 in China
Two billion-dollar weather-related disasters hit the Earth last month, both in China, according to the July 2015 Catastrophe Report from insurance broker Aon Benfield: Typhoon Chan-hom ($1.6 billion in damage) and flooding July 20 - 24 that caused $1.2 billion in damage. With twelve billion-dollar weather disasters so far in 2015, Earth is on pace for its lowest number of such disasters since 2004, when sixteen occurred.

Disaster 1. Typhoon Chan-hom made landfall about 80 mi south-southeast of Shanghai, China on July 11, killing 16 people and doing at least $1.5 billion in damage. The typhoon did another $100 million in damage to Guam, Japan, Taiwan, and Korea. In this image, we see people watching huge waves from Chan-hom pounding Wenling, in east China's Zhejiang province, on July 10, 2015. Image credit: STR/AFP/Getty Images.

Disaster 2. Heavy rainfall in China from July 20 - 24 killed 28 people and did $1.2 billion in damage. More than 238,000 residents were evacuated as floods and landslides destroyed 7,770 homes and damaged 35,100. In this picture, we see vehicles stranded on a flooded road in Wuhan, Hubei Province of China, on July 23, 2015, when 160.2 millimeters (6.31") hit the city. This was their heaviest daily rainfall since 1998, according to Changjiang Times. Image credit: ChinaFotoPress/Getty Images.

Arctic sea ice falls to 8th lowest July extent on record
Arctic sea ice extent during July 2015 was the 8th lowest in the 36-year satellite record, according to the National Snow and Ice Data Center (NSIDC). A large area of high pressure set up shop north of Alaska, and a strong area of low pressure formed over Northeastern Eurasia. The circulation around these features brought sunny skies and a warm flow of air into the Arctic that led to rapid ice loss. This Arctic Dipole pattern also occurred in all the summer months of 2007, and helped support the record 2007 summer reduction in sea ice extent. (Note that the record was beaten in 2012, a year that did not feature an Arctic Dipole pattern.) The Arctic Dipole pattern diminished in early August 2015, but substantial melting has continued into the middle of the month.

Notable global heat and cold marks set for July 2015
Hottest temperature in the Northern Hemisphere: 52.8°C (127.0°F) at Mitribah, Kuwait, July 30
Coldest temperature in the Northern Hemisphere: -22.5°C (-8.5°F) at Summit, Greenland, July 30
Hottest temperature in the Southern Hemisphere: 37.6°C (99.7°F) at Floriano, Brazil, July 10
Coldest temperature in the Southern Hemisphere: -80.2°C (-112.4°F) at Dome A, Antarctica, July 2

Major stations that set (not tied) new all-time heat or cold records in July 2015
Akkuduk (Kazakhstan) max. 46.8°C July 1
Boulogne sur Mer (France) max. 35.4C° July 1
Melun (France) max. 39.4°C July 1
Dieppe (France) max. 38.3°C July 1
Urumita (Colombia) max. 42.2°C July 1
Dzhusaly (Kazakhstan) max. 46.2°C July 2
Volkel (Netherlands) max. 36.9°C July 2
Twenthe (Netherlands) max. 36.1°C July 2
Leeuwarden (Netherlands) max. 34.0°C July 2
Valledupar-Villa Rosa (Colombia) max. 42.4°C July 3
Bad Lippspringe (Germany) max. 37.9°C July 4
Giessen (Germany) max. 38.1°C July 4
Repelon (Colombia) max. 40.9°C July 4
Frankfurt (Germany) max. 39.0°C July 5
Ohringen (Germany) max. 38.5°C July 5
Wurzburg (Germany) max. 38.6°C July 5
Kiztingen (Germany) max. 40.3°C July 5, New national record high for Germany
Kahl (Germany) max. 39.8°C July 5
Bad Durkheim (Germany) max. 39.7°C July 5
Neunkirchen (Germany) max. 39.2°C July 5
Hannover City (Germany) max. 39.0°C July 5
Aigle (Switzerland) max. 36.1°C July 5
Gerona Airport (Spain) max. 41.3°C July 5
Gerona St Daniels (Spain) max. 42.2°C July 5
Cienfuegos (Cuba) max. 37.0°C July 6
Barcelonette (France) max. 34.3°C July 6
Mende (France) max. 36.1°C July 6
Gap (France) max. 36.9°C July 6
Saint-Martin-d’Heres (France) max. 40.7°C July 7
Lezigneux (France) max. 39.9°C July 7
Embrun (France) max. 36.7°C July 7
St Etienne (France) max. 41.1°C July 7
Sainte-Leocadie (France) max. 35.4°C July 7
Grenada Airport (Spain) max. 43.1°C July 7
Grenada City (Spain) max. 43.9°C July 7
Lerida (Spain) max. 43.1°C July 7
Zaragoza (Spain) max. 44.5°C July 7
Geneva (Switzerland) max. 39.7°C July 7
Nyon/Changins (Switzerland) max. 38.0°C July 7
Payerne (Switzerland) max. 37.9°C July 7
Neuchatel (Switzerland) max. 37.8°C July 7
Fribourg (Switzerland) max. 36.6°C July 7
Neuenburg (Switzerland) max. 37.8°C July 7
Wynau (Switzerland) max. 37.2°C July 7
Evolene (Switzerland) max. 28.4°C July 7
Plaffeien (Switzerland) max. 32.0°C July 7
La Fretaz (Switzerland) max. 29.9°C July 7
Oberstdorf (Germany) max. 35.6°C July 7
Innsbruck City (Austria) max. 38.2°C July 7
Qaanaaq (Greenland/Denmark) max. 20.4°C July 8
Ardebil (Iran) max. 40.2°C July 10
Jucaro (Cuba) max. 36.8°C July 10
Riohacha (Colombia) max. 40.6°C July 13
Yuzawa (Japan) max. 36.8°C July 13
Washikura (Japan) max. 29.0°C July 13
Tajima (Japan) max. 34.8°C July 13
Niitsu (Japan) max. 37.9°C July 13
Ogata (Japan) max. 38.3°C July 13
Uozu (Japan) max. 37.9°C July 13
Nanao (Japan) max. 37.4°C July 13
Yamada (Japan) max. 37.5°C July 14
Kasenuma (Japan) max. 36.7°C July 14
Marumori (Japan) max. 37.6°C July 14
Yanagawa (Japan) max. 39.1°C July 14
Kawauchi (Japan) max. 35.7°C July 14
Ononimachi (Japan) max. 35.8°C July 14
Buzaubaj (Uzbekistan) max. 48.2°C July 14
Limoges Airport (France) max. 37.3°C July 16
Grazzanise (Italy) max. 39.8°C July 17
Split Airport (Croatia) max. 39.4°C July 18
Krems (Austria) max. 38.3°C July 19
Senj (Croatia) max. 39.7°C July 22
Rab (Croatia) max. 39.3°C July 22
Zadar Airport (Croatia) max. 39.0°C July 22
Zavizan (Croatia) max. 28.3°C July 22
Ronchi dei Legionari (Italy) max. 39.2°C July 22
Aviano (Italy) max. 38.3°C July 22
Vsetin (Czech Republic) max. 36.8°C July 22
Osako (Japan) max. 36.4°C July 22
Esashi (Japan) max. 37.2°C July 22
Kanayama (Japan) max. 36.1°C July 22
Altai (China) max. 39.5°C July 22
Hoboksar (China) max. 37.7°C July 22
Kaba He (China) max. 41.0°C July 22
Korla (China) max. 40.5°C July 24
Jucaro (Cuba) max. 37.0°C July 28
Contramaestre (Cuba) max. 38.2°C July 29
Isabel Rubio Airport (Cuba) max. 36.3°C July 29
Indio Hatuey (Cuba) max. 38.1°C July 30
Kirkuk (Iraq) max. 50.0°C July 30
Najaf (Iraq) max. 51.5°C July 30
Kanaqin (Iraq) max. 52.0°C July 30
Salahaddin (Iraq) max. 41.1°C July 31
Meigetsu (Japan) max. 37.8°C July 31
Vize Island (Russia) max. 9.2°C July 31

New all-time national and territorial heat records set or tied in 2015
As of August 14, 2015, ten nations or territories tied or set all-time records for their hottest temperature in recorded history in 2015, and one (Israel) set an all-time cold temperature record. For comparison, only two nations or territories set all-time heat records in 2014, and nine did in 2013. The most all-time national heat records held by any year is nineteen in 2010. Most nations do not maintain official databases of extreme temperature records, so the national temperature records reported here are in many cases not official. I use as my source for international weather records researcher Maximiliano Herrera, one of the world's top climatologists, who maintains a comprehensive list of extreme temperature records for every nation in the world on his website. If you reproduce this list of extremes, please cite Maximiliano Herrera as the primary source of the weather records. Wunderground's weather historian Christopher C. Burt maintains a database of these national heat and cold records for 235 nations and territories on's extremes page. Here are the all-time national or territorial heat and cold records set so far in 2015:

Hong Kong set its national heat record on August 9, when the mercury hit 37.9°C (100.2°F) at Happy Valley.
Germany set a new national heat record of 40.3°C (104.5°F) twice this year: on July 5 and on August 7, at the Kitzingen station in Bavaria.
Vietnam tied its national heat record of 42.7°C (108.9°F) at Con Cuong on May 30.
Palau tied its national heat record of 34.4°C (94.0°F) at Koror Airport on May 14.
Venezuela set a new national heat record of 43.6°C (110.5°F) at Coro on April 29.
Laos tied its national heat record of 42.0°C (107.6°F) at Thakhek on April 20.
Ghana set a new national heat record of 43.3°C (109.9°F) at Navrongo on April 10. This is the third time this year Ghana has tied or set a new all-time heat record.
Cocos Islands (Australian territory) tied their all-time heat record with 32.8°C (91.0°F) on April 8.
Equatorial Guinea set a new national heat record of 35.5°C (95.9°F) at Bata on March 17.
Wallis and Futuna Territory (France) set a new territorial heat record with 35.5°C (95.9°F) on January 19 at Futuna Airport.

Israel set a new national cold record of -14.2°C (6.4°F) at Merom Golan on January 10.

Special Mentions:
Antarctica set a new heat record for its mainland of 17.5°C (63.5°F) at Esperanza Base on March 24. Previous record: 17.4°C (63.3°F) at Marambio Base, set the previous day. The World Meteorological Organization (WMO) has appointed a committee to study this event and determine if this represents an official record for the continent. Note that this is a record for mainland Antarctica, not a territorial or continental record. The all-time maximum record for the continent and territory of Antarctica is 19.8°C (67.6°F) on January 30, 1982, in Signy Island, South Orkney, an island group located about 450 miles northeast of the tip of the Antarctic Peninsula, the northernmost portion of mainland Antarctica. Geologically, the South Orkney are on the Antarctic plate, and politically, they are part of Antarctica. This record was improperly listed as a territorial record for Antarctica in May's global summary.

Switzerland had its highest reliably measured temperature on record in Geneva on July 7, when the mercury hit 103.5°F (39.7°C). The only higher temperature ever measured in the country was a 106.7°F (41.5°C) reading on August 11, 2003 at Grono. As reported at the Swiss news site, this old record was achieved "using an old measurement technique of weather huts, which generally recorded temperatures a few degrees higher than modern instruments." Weather records researcher Maximiliano Herrera agrees that this year's 39.7°C reading in Geneva is the highest reliably measured temperature ever in Switzerland, though the August 11, 2003 temperature at Grono was probably warmer (near 40°C), after correcting for the known problems with the site.

Samoa was originally listed by Mr. Herrera as tying its national heat record with 36.5°C (97.7°F) on January 20 at Asau, but a subsequent review of the record revealed possible issues with the measurement equipment, so this record is dubious.

Kudos also to Mr. Herrera for supplying the data for the "Notable global heat and cold marks set for July 2015" and "Major stations that set (not tied) new all-time heat or cold records in July 2015" sections.

Danny strengthens slightly; 93C likely to become Hurricane Kilo and approach Hawaii
Tiny Hurricane Danny continues to gradually strengthen in the central Atlantic. At 5:00 p.m. EDT, Danny’s top sustained winds were up to 80 mph. Danny was still located far out to sea—more than 1000 miles east of the Windward Islands, moving west-northwest at just 10 mph—and there are no major changes to the outlook for Danny from our post this morning. Meanwhile, Invest 93C has been upgraded to Tropical Depression 3 in the central Pacific, and the Central Pacific Hurricane Center projects TD 3-C to become Hurricane Kilo by Saturday, perhaps curving toward the western Hawaiian islands as a Category 2 hurricane by Monday. We’ll have a full update on both systems by 1 PM ET Friday. See also Steve Gregory’s update from earlier this afternoon.

Jeff Masters and Bob Henson

About the Blogs
These blogs are a compilation of Dr. Jeff Masters,
Dr. Ricky Rood, and Angela Fritz on the topic of climate change, including science, events, politics and policy, and opinion.