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Earth Matters

Kigali: A Huge Step Forward for Climate

October 27th, 2016 by Kathryn Hansen

View of the dais during the High-Level Segment Ministerial Round Table ‘Towards an Agreement on the HFC Amendment under the Montreal Protocol – Part 2: Ensuring Benefits for All.’ October 14, 2016 (day 6). Photo by IISD/ENB | Kiara Worth

The Antarctic ozone hole in 2016 was not exactly remarkable. But each year, we publish an annual update because, when strung together over time, the series shows the unparalleled success of the Montreal Protocol in stabilizing the atmosphere.

Now the scientists and negotiators behind the Protocol are taking on a new problem: the climate warming effects of chemicals that were supposed to be better for the ozone layer. NASA scientist Paul Newman attended the Montreal Protocol’s international meeting this October in Kigali, Rwanda, and he sat down with us to explain the new agreement, why it’s unique, and what it was like to participate in the meeting. Here are some of the main takeaways:

  • The Montreal Protocol is not just about ozone depleting substances; it’s also about their replacements.

“The Montreal Protocol is written so that we can control ozone-depleting substances and their replacements. Chlorofluorocarbons (CFCs) were initially replaced with hydrochlorofluorocarbons (HCFCs) and then hydrofluorocarbons (HFCs), making HFCs the so-called “grandchildren” of the Montreal Protocol.

HFCs very weakly affect the ozone layer. But the problem is that they are powerful greenhouse gases. One can of this keyboard cleaner [an aerosol can with HFC-134a] is equivalent to 1,360 cans of carbon dioxide. HCFs are much more powerful than carbon dioxide as a greenhouse gas, and that’s true of many HFCs, not just HFC-134a. And their use—particularly in refrigeration and air conditioning—has been going up fast.

It has been projected that by 2100, the effect of HFCs on temperature could be as high as 0.5 Kelvin (0.5 degrees Celsius, or 0.9 degrees Fahrenheit) if we did nothing. Because of the amendment, that number will be closer to 0.06 Kelvin (0.06 degrees Celsius, or 0.11 degrees Fahrenheit).

The point of the of Kigali amendment was to control these greenhouse gases because they are a replacement for CFCs. They are adding to the climate problem, so the world’s nations wanted to do something about it. The Montreal Protocol has evolved from strictly an ozone treaty, to an ozone and climate treaty.”

NASA scientist Paul Newman (right) on October 10, 2016 (day 2). Photo by IISD/ENB | Kiara Worth

  • The amendment looks into the future because the accumulation and removal of HFCs in the atmosphere takes a while.

“HFCs go through a series of steps before they can begin accumulating in the atmosphere. The first is production, in which factories make tanks of the gas (like a brewery making big vats of beer). The next step is consumption, when HFCs are added to things like refrigerators and air conditioners (to follow the beer analogy, that’s when the brewer puts the beer in a bottle or keg). Finally, HFCs are emitted when people use those things (pop the cork on the bottle or tap the keg).

The important point is that there is a time lag. Consumption of HFCs are projected to peak in the late 2020s, but emissions don’t peak until about 2035. Once in the atmosphere, HFCs last a long time before being destroyed by chemical reactions. For example, If I vent my can of 134a, 5 percent of it will still be in the atmosphere after 42 years. So they continue to accumulate and peak in the atmosphere by the mid 2050s.”

Delegates during the morning plenary on October 11, 2016 (day 3). Photo by IISD/ENB | Kiara Worth

  • Montreal Protocol meetings can be exhausting …

“Montreal Protocol meetings don’t have a schedule; they have an agenda. That means that we have a list of topics and we work until they are all addressed. For example, we worked all day Friday (October 14, 2016) but didn’t finish, so we reconvened Saturday at 1 a.m. and finished the amendment at 7 a.m. I was up for 27 straight hours, tired and hungry.”

… but uniquely effective.

“This agreement is a huge step forward because it is essentially the first real climate mitigation treaty that has bite to it. It has strict obligations for bringing down HFCs, and is forcing scientists and engineers to look for alternatives.

The Montreal Protocol is also technically the perfect mechanism for dealing with these issues. The technology people, economics people, science people, chemical manufacturers—they have all worked through the Montreal Protocol and are fully capable of dealing with refrigerants like HFCs and their alternatives.

The agreement wouldn’t go forward without a pretty good idea about what those replacements might be. Hydrofluoroolefins, for example, have a really tiny climate impact and only 10-day lifetimes and are already being used in some applications. The Montreal Protocol is pro-engineering, pro-technology, and very different than any other treaty. We can solve our environmental problems—that is the power of a technological society.”

October 2016 Puzzler

October 24th, 2016 by Pola Lem


Every month on Earth Matters, we offer a puzzling satellite image. The October 2016 puzzler is above. Your challenge is to use the comments section to tell us what part of the world we are looking at, when the image was acquired, what the image shows, and why the scene is interesting.

How to answer. Your answer can be a few words or several paragraphs. (Try to keep it shorter than 200 words). You might simply tell us what part of the world an image shows. Or you can dig deeper and explain what satellite and instrument produced the image, what spectral bands were used to create it, or what is compelling about some obscure speck in the far corner of an image. If you think something is interesting or noteworthy, tell us about it.

The prize. We can’t offer prize money or a trip to Mars, but we can promise you credit and glory. Well, maybe just credit. Roughly one week after a puzzler image appears on this blog, we will post an annotated and captioned version as our Image of the Day. In the credits (and also on this blog), we will acknowledge the person who was first to correctly ID the image. We may also recognize certain readers who offer the most interesting tidbits of information about the geological, meteorological, or human processes that have played a role in molding the landscape. Please include your preferred name or alias with your comment. If you work for or attend an institution that you want us to recognize, please mention that as well.

Recent winners. If you’ve won the puzzler in the last few months or work in geospatial imaging, please sit on your hands for at least a day to give others a chance to play.

Releasing Comments. Savvy readers have solved some of our puzzlers after only a few minutes or hours. To give more people a chance to play, we may wait between 24-48 hours before posting the answers we receive in the comment thread.

Good luck!

Editor’s Note: Congratulations to Peter Gunnarsson, and James Varghese for being some of the first readers to solve the puzzler on Facebook. Congratulations to Vera Maria for being the first to weigh in with the answer on Earth Matters. See a labeled version of the October puzzler here.

September 2016 was Warmest on Record by Narrow Margin

October 18th, 2016 by Michael Cabbage & Leslie McCarthy

September 2016 was the warmest September in 136 years of modern record-keeping, according to a monthly analysis of global temperatures by scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York.


NASA Earth Observatory chart by Joshua Stevens, based on data from the NASA Goddard Institute for Space Studies.

September 2016’s temperature was a razor-thin 0.004 degrees Celsius warmer than the previous warmest September in 2014. The margin is so narrow those two months are in a statistical tie. Last month was 0.91 degrees Celsius warmer than the mean September temperature from 1951-1980.

The record-warm September means 11 of the past 12 consecutive months dating back to October 2015 have set new monthly high-temperature records. Updates to the input data have meant that June 2016, previously reported to have been the warmest June on record, is, in GISS’s updated analysis, the third warmest June behind 2015 and 1998 after receiving additional temperature readings from Antarctica. The late reports lowered the June 2016 anomaly by 0.05 degrees Celsius to 0.75.

“Monthly rankings are sensitive to updates in the record, and our latest update to mid-winter readings from the South Pole has changed the ranking for June,” said GISS director Gavin Schmidt. “We continue to stress that while monthly rankings are newsworthy, they are not nearly as important as long-term trends.”

The monthly analysis by the GISS team is assembled from publicly available data acquired by about 6,300 meteorological stations around the world, ship- and buoy-based instruments measuring sea surface temperature, and Antarctic research stations. The modern global temperature record begins around 1880 because previous observations didn’t cover enough of the planet. Monthly analyses are updated when additional data become available, and the results are subject to change.

Related Links
+ For more information on NASA GISS’s monthly temperature analysis, visit:

+ For more information about how the GISS analysis compares to other global analysis of global temperatures, visit:

+ To learn more about climate change and global warming, visit:

Hurricane Roundup: Matthew from Above

October 14th, 2016 by Pola Lem


After Hurricane Matthew ripped through Haiti, it blew through the Southeast. From above, NASA satellites, aircraft, and astronauts kept watch on the storm. The Earth Observatory published several images of the destructive storm (thumbnails above). The below includes a sampling of other notable images and maps related to the storm.

Soil Moisture
Matthew drenched the Carolinas, breaking records for single day rainfall in six places, The Washington Post reported. The Southeast received a total of 13.6 trillion gallons of water—that’s three-fourths the volume of the Chesapeake Bay. Hard-hit areas of North Carolina received 15 inches (38 centimeters) of rain.

That downpour saturated the area, causing values for soil moisture to increase substantially. The North American Land Data Assimilation System (NLDAS) mapped these values for October 1, 2016.

Even before the storm arrived, the ground in many areas was saturated. Eastern North Carolina and northeastern South Carolina have localized areas over the 98th percentile. That means that on October 1, the soil was wetter than it was on that date in 98 percent of previous years. The already-wet soils and heavy precipitation from Matthew led to significant flooding in these areas.


Image: NASA

Temperature and Precipitation
The Jet Propulsion Laboratory (JPL) HAMSR instrument flew above Hurricane Matthew on October 7, 2016, aboard a NASA Global Hawk aircraft. The image below shows atmospheric temperatures overlaid atop ground-based radar and satellite visible images, according to a JPL release. Reds tones show a lack of clouds, whereas blue tones show ice and heavy precipitation. At the top left is an image taken from the Global Hawk.



Clouds Swirling from Above
Expedition 49 astronaut Kate Rubins took the photograph below from the International Space Station at 21:05 Universal Time, on October 4, 2016, as the hurricane approached the Florida coast. Hurricane clouds fill the shot, which includes the station’s solar arrays.


Photo: NASA/Kate Rubins


Heavy rains fell on Louisiana in August 2016, causing record-high crests for a number of rivers in the area. Map by Joshua Stevens/NASA Earth Observatory.

In the United States, we say “it’s raining cats and dogs” when we get a heavy downpour. In South Africa, it rains “women with clubs.” In Slovakia, a good soak means “tractors are falling.”

World languages brim with rainy day idioms. But when it comes to describing copious amounts of wet stuff, meteorologists do not encourage wordplay. Researchers are particularly adamant about one expression that does not work: the “rain bomb.”

The summer of 2016 brought extreme rain to multiple parts of the U.S., taking lives and causing billions  in property damage. In July, thunderstorms dumped more than six inches of rain on Elicott City, Maryland in roughly two hours, causing flash floods that upended cars and lives. In May, nearly eight inches of rain fell in two days, among a series of heavy rains to inundate Texas. Most recently in Louisiana, more than 30 inches of rain fell in three days, stranding 20,000 people and killing nine.

The Louisiana storm didn’t meet the criteria of a tropical depression as defined by the National Hurricane Center: a tropical cyclone in which the maximum sustained surface wind speed is 38 miles per hour (62 kilometers per hour) or less. In another instance of precise wording, 2012’s Hurricane Sandy technically ceased to be a “hurricane” a few hours before it made landfall, turning into a “post-tropical cyclone.”

For some in the media, “tropical depression” lacks pizzazz and conviction. It lacks the visceral pelting of tractors falling out of the sky or of women with clubs beating down on the Earth. Some news organizations referred to the Louisiana event as a rain bomb. So what should we call severe rain?

NASA scientists George Huffman and Owen Kelley parsed some of the commonly-used rain terminology.  

For one, there’s the “rain shaft.” A rain shaft is a centralized column of precipitationnot necessarily heavy rain. “The rain shaft […] is any rain event, no matter how modest or foreboding, that can be seen stretching from the cloud to the ground,” wrote Huffman, a research meteorologist at NASA’s Goddard Space Flight Center.

Then, there are “microbursts.” These are severe wind events caused by a “small column of exceptionally intense and localized sinking air that results in a violent outrush of air at the ground,” according to AccuWeather. Microbursts are smaller than 2.5 miles (4 kilometers) in size.

Be careful of mixing rain shafts with microbursts, Huffman cautioned.

“Just as you don’t have a microburst with every rain shaft, you don’t necessarily have an identifiable rain shaft with every microburst,” wrote Huffman in an email. “The really interesting dynamics of microbursts are a bit rare, and frequently not present in flooding rains.”

There’s also a size distinction between the different systems, NASA scientists said. A rain shaft comes out of an individual convective cell, making it roughly five to ten kilometers across. (By contrast, tropical depressions measure roughly 100 to 500 kilometers across.)

But in some cases, like Louisiana’s, the term “tropical depression” works, said Owen Kelley. “You don’t need to appeal to rain shafts, microbursts, or rain bombs to explain this system,” Kelley wrote in an email. The storm in Louisiana was “just a plain-old tropical depression that got stuck in one place for several days in a row and therefore dumped a lot of rain in one place.” That weather system did display some of the common signs of a tropical system. For instance, Huffman notes that it had low pressure at low and middle altitudes, and high pressure at the top, “implying some degree of warm core.” (Mid-latitude systems have a cold core, with the most negative pressure deviation at the system’s top.)

Researchers agree, though, about one term, “rain bomb,” which appeared in a couple of articles this summer in reference to extreme rainfall events. Don’t use it, scientists said. While it makes for a catchy headline, “rain bomb” is not an established meteorological term.  

For extreme rain, Kelley suggested yet another phrase: “vigorous convective cells.” These severe rainstorms can take on various forms: super-cells, squall lines, isolated cells.

Microbursts, rain shafts, vigorous convective cells. At the end, isn’t it all just wet stuff coming out of the sky? Yes and no, scientists say. Terms used to describe extreme rain should be used with an eye on precision. As extreme rains (and extreme weather, in general) become more frequent, so will the terms we use to describe them.