Friday, June 17, 2016

Ocean Heat Overwhelming North Atlantic

Arctic sea ice extent on June 19, 2016, was at a record low for the time of the year, as the (updated) image below shows.

[ image from JAXA ]
Not only is Arctic sea ice extent at record low for time of year, the sea ice is also rapidly getting thinner, more fractured, lower in concentration and darker in color. 

[ Cracks in sea ice north of Greenland on June 19, 2016, created with Arctic-io image ]
On the morning of June 20, 2016, strong methane releases were recorded over the water north of Greenland, as well as east of Greenland, as illustrated by the image below.

The image below shows that on the morning of June 20, 2016, mean global methane levels had increased be several parts per billion over a large altitude range, compared to the two previous days. Methane levels at selected altitudes on days in July 2015 and December 2015 are added for reference.
[ click on images to enlarge ]
Temperatures in the Arctic are rising, as illustrated by the image below, showing that on June 19, 2016, temperatures were as high as 31.4°C or 88.4°F over the Mackenzie River (green circle) which ends in
the Arctic Ocean (and thus warms up the Arctic Ocean there).


On June 20, 2016, the Sun will reach its highest point (Solstice), and the Arctic will have 24 hours sunlight, i.e. on the Arctic Circle (latitude 66.56° north) or higher. The Arctic is about 20,000,000 square km (7,700,000 square miles) in size and covers roughly 4% of Earth's surface. Insolation during the months June and July is higher in the Arctic than anywhere else on Earth, as illustrated by the image below, by Pidwirny (2006).


Sea surface temperature near Svalbard was as high as 55°F (or 12.8°C, at the green circle) on June 14, 2016, an anomaly of 19.6 °F (or 10.9°C) from 1981-2011, as illustrated by the image below.


[ click on images to enlarge ]
Above image, created with nullschool.net, further shows that the cold lid that had been growing so prominently in extent over the North Atlantic over the past few years, has shrunk substantially. By comparison, the cold area over the North Pacific has grown larger. This is further confirmed by the image on the right, created with NASA maps and showing ocean temperature anomalies for May 2016.

Plenty of meltwater has run off from Greenland in 2016, as illustrated by the NSIDC.gov image on the right. The run-off from Alaska and Siberia into the Pacific seems less by comparison than the run-off into the North Atlantic. So, how could it be that the cold area in the North Pacific has grown larger than the cold area in the North Atlantic?
[ click on images to enlarge ]

Could there be another factor influencing the size of these cold areas in the North Atlantic and the North Pacific?

The image below, created with NOAA images, gives a comparison between the situation on June 1, 2015 (top), and June 1, 2016 (bottom), showing anomalies from 1961-1990.


Sunday, June 5, 2016

High Temperatures In Arctic

0-2000 m Global Ocean Heat Content
Ocean heat content is rising, as illustrated by the image on the right. Where the sea ice declines, this is causing high air temperatures in the Arctic.

This year (from January to April 2016) on the Northern Hemisphere, oceans were 0.85°C or 1.53°F warmer than the 20th century average.

The image below illustrates that temperatures look set to be high in Siberia for the coming week. The panel on the right shows anomalies at the top end of the scale in Eastern Siberia on June 5, 2016, while the panel on the right shows a forecast for June 12, 2016.


These high air temperatures are causing feedbacks that are in turn further speeding up warming in the Arctic.

Warmer Rivers

Temperatures as high as 28.9°C or 83.9°F were recorded over the Mackenzie River close to the Arctic Ocean on June 13, 2016, at location marked by the green circle.


Below is a satellite image of the Mackenzie River delta on June 11, 2016


The image below shows that temperatures as high as 36.6°C or 97.8°F were forecast for June 13, 2016, over the Yenisei River in Siberia that ends in the Arctic Ocean.


Wildfires

Earlier this month, temperatures in Eastern Siberia were as high as 29.5°C (85°F). This was on June 5, 2016, at a location close to the coast of the Arctic Ocean (green circle).


High air temperatures come with increased risk of wildfires, as illustrated by the image below showing carbon monoxide levels as high as 2944 ppb on June 4, 2016 (at green circle).


The satellite image below zooms into the area with these high carbon monoxide readings, showing wildfires on Kamchatka Peninsula on June 3, 2016.


Albedo Loss

The image on the right shows that, this year, April snow cover on the Northern Hemisphere was the lowest on record. The added trend points at a total absence of snow by the year 2036.

Professor Peter Wadhams, head of the Polar Ocean Physics Group at Cambridge University, says: “My prediction remains that the Arctic ice may well disappear, that is, have an area of less than one million square kilometres for September of this year.”

Warming due to Arctic snow and ice loss may well exceed 2 W per square meter, i.e. it could more than double the net warming now caused by all emissions by people of the world, Peter Wadhams calculated in 2012.

Seafloor Methane

Peter Wadhams further co-authored a study that calculated that methane release from the seafloor of the Arctic Ocean could yield 0.6°C warming of the planet in 5 years (see video interview of Thom Hartmann with Peter Wadhams below).



Combined Impact Of Multiple Feebacks

In conclusion, high air temperatures in the Arctic are very worrying, as they can trigger a number of important feedbacks, i.e. the ones discussed above and further feedbacks such as:
  • Changes to Jet Streams. As the Arctic warms more rapidly than the rest of Earth, changes are occurring to the jet streams. As a result, winds can increasingly bring hot air far to the north, resulting in further loss of the Arctic snow and ice cover, in turn further warming up the Arctic.
  • Warmer Rivers. High air temperatures cause warming of the water of rivers that end up in the Arctic Ocean, thus resulting in additional sea ice decline and warming of the Arctic Ocean all the way down to the seabed.
  • Wildfires. High air temperatures set the scene for wildfires that emit not only greenhouse gases such as carbon dioxide and methane, but also pollutants such as carbon monoxide that depletes hydroxyl that could otherwise break down methane, and black carbon that, when settling on ice, causes it to absorb more sunlight (see under albedo loss), besides being a climate forcer when in the atmosphere.
  • Soil destabilization. Heatwaves and droughts destabilize the soil. Soil that was previously known as permafrost, was until now held together by ice. As the ice melts, organic material in the soil starts decomposing, resulting in emissions of methane and carbon dioxide, while the soil becomes increasingly vulnerable to wildfires.
  • Buffer Loss. Arctic snow and ice cover acts as a buffer, absorbing heat that in the absence of this buffer will have to be absorbed by the Arctic Ocean, as discussed in earlier posts such as this one
  • Albedo Loss. Arctic snow and ice cover make that sunlight is reflected back into space. In the absence of this cover, the Arctic will have to absorb more heat.
  • Seafloor Methane. As sediments at the seafloor of the Arctic Ocean warm, hydrates contained in these sediments could be destabilized and release huge quantities of methane.

How much warmer could it be within one decade?

The two feedbacks mentioned by Peter Wadham (albedo and seafloor methane) are are depicted in the image below.

for further discussion, see the feedbacks page
The combined global temperature rise over the next decade due to these two feedbacks (albedo and seafloor methane) alone may be 0.4°C or 0.72°F for a low-rise scenario and may be 2.7°C or 4.9°F for a high-rise scenario.

Additionally, as temperatures rise, further feedbacks will kick in more strongly, further accelerating the rise in temperature, as also discussed in earlier posts such as this one.

When also including further feedbacks, warming could exceed 10°C (18°F) within one decade, assuming that no geoengineering will take place within a decade, as discussed in earlier posts such as this one.

The situation is dire and calls for comprehensive and effective action, as described at the Climate Plan.

Links

• Climate Plan
http://arctic-news.blogspot.com/p/climateplan.html

• Feedbacks in the Arctic
http://arctic-news.blogspot.com/p/feedbacks.html

• East Siberian Heatwave
http://arctic-news.blogspot.com/2015/07/east-siberian-heat-wave.html

• Wildfire Danger Increasing
http://arctic-news.blogspot.com/2016/05/wildfire-danger-increasing.html

• Albedo changes in the Arctic
http://arctic-news.blogspot.com/2012/07/albedo-change-in-arctic.html

• Three kinds of warming in the Arctic
http://arctic-news.blogspot.com/2016/02/three-kinds-of-warming-in-arctic.html

• Arctic could become ice-free for first time in more than 100,000 years, claims leading scientist
http://www.independent.co.uk/environment/climate-change/arctic-could-become-ice-free-for-first-time-in-more-than-100000-years-claims-leading-scientist-a7065781.html

• Greenhouse gas levels and temperatures keep rising
http://arctic-news.blogspot.com/2016/01/greenhouse-gas-levels-and-temperatures-keep-rising.html

• Arctic Methane Release: "Economic Time Bomb"
http://arctic-news.blogspot.com/2013/07/arctic-methane-release-economic-time-bomb.html

• February Temperature
http://arctic-news.blogspot.com/2016/03/february-temperature.html

• September 2015 Sea Surface Warmest On Record

Saturday, May 28, 2016

How Much Warming Have Humans Caused?

How much did temperatures rise since 1900?

Differences in baseline (reference period) can result in dramatic differences in temperature rise. The U.K. Met Office HadCRUT4 dataset typically presents temperature anomalies relative to a 1961-1990 baseline. NASA typically uses a 1951-1980 baseline, but the NASA website allows for different baselines to be selected. When selecting a 1961-1990 baseline, the temperature of the past period of six months was 1.05°C (1.89°F) higher than this baseline, as illustrated by the NASA map in the left panel of the image below. But when compared to 1890-1910, the temperature of the past period of six months was 1.48°C (or 2.664°F) higher, as illustrated by the NASA map in the right panel of the image below.


A polynomial trend can reduce variability such as caused by volcanoes and El Niño events. The graph below was created with the NASA L-OTI monthly mean global surface temperature anomaly, which has a 1951-1980 baseline, and then with 0.29°C added, which makes the anomaly 0°C in the year 1900 for the added polynomial trend.



This gives an idea of how much temperatures have risen since the year 1900, with a rise for both February and March 2016 showing up that was more than 1.5°C, as also illustrated by the image below. The trend further points at temperature anomalies that will be more than 1.5°C (from 1900) within a decade and more than 2°C soon thereafter.


Temperature Rise before 1900

To see by how much temperatures have risen compared to pre-industrial levels, we need to go back further than 1900. The graph below shows that carbon dioxide concentrations have gone up and down between levels of roughly 180 ppm and 280 ppm over the past 800,000 years. Recently, carbon dioxide levels reached a peak of well above 400 ppm (411 ppm peak hourly average on May 11, 2016).


The image below, from an earlier post, shows how in the past, over the past 420,000 years, temperatures have gone up and down within a window of approximately 10°C (18°F), in line with cycles in the Earth orbit (Milankovitch cycles). Levels of carbon dioxide and methane have gone up and down accordingly, with carbon dioxide moving between 180 ppm and 280 ppm and methane roughly between 300 ppb and 700 ppb.


Meanwhile, carbon dioxide concentrations have been as high as 411 ppm (as discussed further above), i.e. a 131 ppm rise on top of the historic maximum of 280 ppm. The rise in methane concentrations is even steeper, as discussed at the Methane page.

Has the rise in greenhouse gases due to emissions by humans set the scene for a temperature rise of some 10°C (18°F) above 1750 levels, and how rapidly could such a temperature rise eventuate? Could warming caused by humans result in a temperature rise of more than 10°C (18°F) within a decade?

In its First Assessment Report, the IPCC explains that temperatures have come down since the Holocene peak, i.e. the natural maximum of the most recent Milankovitch cycle (image right, top panel). As the bottom panel shows, temperatures have risen since the 1600s. There has been a rise from the year 1750 to the year 1900 and there has been a further rise from the year 1900 onward up to recent times (the dotted line indicates the temperature at the year 1900).

The graph on the right, created by Jos Hagelaars, shows that temperatures started rising some 20,000 years ago, reaching a peak some 7000 years ago (in the blue part of the graph). For more detail, also see the comic added at the end of this post.

The graph underneath, based on work by Marcott et al., focuses on this blue part of the graph, while using a 1961-1990 baseline. Temperatures reached a peak some 7000 years ago, and then came down to reach a low a few hundred years ago.

The peak and the bottom temperatures (highlighted in red on image on the right below) for that period suggest there was a fall of more than 0.7°C.


So, a few hundred years ago, temperatures were falling and they would have kept falling, in line with the Milankovitch cycles, had there been no warming caused by humans.

From that bottom point, temperatures first rose by about 0.4°C, overwhelming the downward trend that would otherwise have taken temperatures down further, and then there was an additional rise of at least 1.05°C, when using a baseline of 1961-1990, indicating that humans caused a total of at least 1.45°C warming.

Lewis & Maslin (2015) suggest that, because CO2 began to rise from a low point in 1610, that year could be taken as the start of the Anthropocene. The image on the right also shows that the year 1750 was a low point for CO2 levels and temperature, i.e. well below the baseline of 1961-1990.

The image below shows Northern Hemisphere temperature reconstructions by Moberg et al.


The image on the right is from BerkeleyEarth.org. The wider fluctuations back in time reflect volcanic activity and greater uncertainty, while a simple fit shows a temperature rise of 1.5°C in the past 250 years (1750-2000), of which about 0.9°C occurred in the past 50 years.

Humans have caused even more warming?

The situation looks to be even worse than what the above figures may suggest. Indeed, the bottom low point in the Marcott graph would have been even lower had there been no warming by humans.
The fact that humans did cause substantial warming between 1800 and 1900 is illustrated by the graph below, from a recent post by Michael Mann, who adds that some 0.3°C greenhouse warming had already taken place between the year 1800 and the year 1900.

Some 0.3C greenhouse warming had already taken place by 1900, and some 0.2C warming by 1870
Further studies suggest that humans also caused substantial warming well before 1800, as illustrated by the image on the right. While this study focuses on Europe, it does suggest a rise from 1600 to 1800.

Another example of warming caused by humans before 1800 is presented in research by Dull et al., which suggests that burning of Neotropical forests increased steadily in the Americas, peaking at a time when Europeans arrived in the late fifteenth century. By 1650, some 95% of the indigenous population had perished. Regrowth of forests led to carbon sequestration of some 2 to 5 Pg C, thereby contributing to a fall in atmospheric carbon dioxide recorded in Antarctic ice cores from about 1500 through 1750.

Since at least the fourth century A.D., coal has
been burned in China. W. F. Ruddiman further points in a 2007 paper at human emissions from burning biomass and irrigation, livestock and human waste, and the resulting climate system feedbacks. As illustrated by the image on the right, this had already caused substantial warming prior to the industrial revolution.

In conclusion, substantial warming took place before 1900, making that temperatures were higher than what they would have been had humans caused no warming. Greenhouse gases emitted by people held off a temperature fall that would otherwise have naturally occurred, and they caused a temperature rise on top of that.

Paris Agreement

NASA data suggest that it was 1.48°C (or 2.664°F) warmer than in 1890-1910 for the period from November 2015 to April 2016. Note again that this 1890-1910 baseline is much later than pre-industrial times. The Paris Agreement had pledged to limit the temperature rise to 1.5°C above pre-industrial levels. On land on the Northern Hemisphere, it was 1.99°C (or 3.582°F) warmer (right map of the image below).

[ Temperature anomalies for the period from November 2015 to April 2016, see also comments ]
The above images only account for a half-year period (November 2015 to April 2016), so they are only indicative for what the total rise will be for the year 2016. Nonetheless, when taking into account warming caused by people before 1900, the year 2016 looks set to hit or even exceed the guardrails that the Paris Agreement had pledged would not be crossed. The situation looks even worse when considering that temperatures measured in ice cores already included a substantial amount of warming due to humans even before the start of the Industrial Revolution.

February 2016 was 1.67°C (3°F) warmer than 1890-1910
Again, at the Paris Agreement nations pledged to hold the increase in the global average temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels.

When looking at a single month, February 2016 was 1.67°C (3°F) warmer than 1890-1910 (see image right). When adding a mere 0.34°C to account for warming before 1900, total warming in February 2016 did exceed 2°C. Looking at it that way, the guardrails set in Paris in December 2015 were already crossed in February 2016.

Situation

So, what is the situation? On the one hand, there's the current observed temperature rise (∆O). This rise is typically calculated as the difference between the current temperature and the temperature at a given baseline.

However, this ∆O does not reflect the full impact of human emissions. Temperatures would have been lower had there been no emissions by humans. The full warming impact due to people's greenhouse gas emissions therefore is ∆E. This ∆E is higher than the often-used observed rise, since the baseline would have been lower without warming caused by humans, i.e. including the warming that was already caused before the year 1750.

At the same time, part of global warming caused by people is currently masked due the aerosol emissions (∆M). Such aerosol emissions result mainly from burning of fossil fuel and biomass. There's no doubt that such emissions should be reduced, but the fact remains that the current temperature rise may increase substantially, say, by half when the masking effect disappears.

Thus, the full (unmasked) current warming caused by humans is the sum of these two, i.e. ∆E + ∆M, and the sum could be well over 3°C.

In addition, there is a future temperature rise that's already baked into the cake (∆F). Some feedbacks are not yet very noticeable, since some changes take time to become more manifest, such as melting of sea ice and non-linear changes due to feedbacks that are only now starting to kick in. Furthermore, the full effect of CO2 emissions reaches its peak only a decade after emission, while even with the best efforts, humans are likely to still be causing additional emissions over the coming decade. All such factors could jointly result in a temperature rise greater than ∆E + ∆M together, i.e. ∆F could alone cause a temperature rise of more than 5°C within a decade.

In summary, total anthropogenic global warming warming (∆A) or all warming caused by humans (∆E + ∆M + ∆F) could be more than 10°C (18°F) within one decade, assuming that no geoengineering will take place within a decade.

[ image added later from this post, click on images to enlarge ]

The situation is dire and calls for comprehensive and effective action as described in the Climate Plan.

[ image from xkcd.com/1732 ]


Links

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html

• Feedbacks
https://arctic-news.blogspot.com/p/feedbacks.html

• Extinction
https://arctic-news.blogspot.com/p/extinction.html

• Methane Erupting From East Siberian Arctic Shelf
https://arctic-news.blogspot.com/2014/11/methane-erupting-from-east-siberian-arctic-shelf.html

• Jos Hagelaars' graph, created with graphs by Shakun et al., Marcott et al. and more, is at:
https://ourchangingclimate.wordpress.com/2013/03/19/the-two-epochs-of-marcott/

• Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation, by Shakun et al.
http://www.nature.com/nature/journal/v484/n7392/full/nature10915.html

• A Reconstruction of Regional and Global Temperature for the Past 11,300 Years, by Marcott et al.
http://science.sciencemag.org/content/339/6124/1198

• The Columbian Encounter and the Little Ice Age: Abrupt Land Use Change, Fire, and Greenhouse Forcing, by Dull et al., in:
https://www.sciencenews.org/article/columbus-arrival-linked-carbon-dioxide-drop

• Arctic Climate Records Melting
https://arctic-news.blogspot.com/2016/05/arctic-climate-records-melting.html

• 2500 Years of European Climate Variability and Human Susceptibility, Ulf Büntgen et al. (2011)
http://science.sciencemag.org/content/331/6017/578

• Paris Agreement
https://arctic-news.blogspot.com/2015/12/paris-agreement.html
http://unfccc.int/documentation/documents/advanced_search/items/6911.php?priref=600008831
https://unfccc.int/resource/docs/2015/cop21/eng/l09r01.pdf

• February Temperature
https://arctic-news.blogspot.com/2016/03/february-temperature.html

• Defining the Anthropocene, Lewis & Maslin (2015)
http://www.nature.com/nature/journal/v519/n7542/full/nature14258.html

• Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data, Anders Moberg et al. (2005)
http://www.nature.com/nature/journal/v433/n7026/full/nature03265.html

• The early anthropogenic hypothesis: Challenges and responses, by W.F. Ruddiman (2007)
http://onlinelibrary.wiley.com/doi/10.1029/2006RG000207/abstract

• Berkeley Earth, Summary Of Findings
http://berkeleyearth.org/summary-of-findings

• Reconciling divergent trends and millennial variations in Holocene temperatures, by Marsicek et al. (2018)
https://www.nature.com/articles/nature25464

Reconciling divergent trends and millennial
variations in Holocene temperatures
Jeremiah Marsicek


Saturday, May 21, 2016

Arctic Climate Records Melting

An intensely warm winter and spring are melting climate records across Alaska, reports NOAA in the post 'Arctic set for record-breaking melt'. The January-April 2016 period was 11.4°F (6.4°C) warmer than the 20th century average, reports NOAA. The NOAA image below further illustrates the situation.
The sea ice is melting rapidly. Warm water from the Mackenzie River contributes to dramatic melting in the Beaufort Sea, as illustrated by the image below, showing that on May 20, 2016, the Arctic Ocean was 5°F (2.8°C) warmer than in 1981-2011 at the delta of the Mackenzie River.


The image below shows that on May 20, 2016, sea ice extent was 10.99 million square km, compared to the 12.05 million square km extent of the sea ice in May 20, 2012, as measured by JAXA


Sea ice reached a record minimum extent of 3.18 million square km on September 15, 2012, and chances are that the sea ice will be largely gone by September 2016.

The year 2016 is an El Niño year and insolation during the coming months of June and July is higher in the Arctic than anywhere else on Earth. Higher temperatures come with increased danger of wildfires. Greenhouse gases are at record high levels: in April and may, CO2 was about 408 ppm, with hourly peaks as high as 411 ppm (on May 11, 2016). Methane levels are high and rising, especially over the Arctic. Smoke and methane are speeding up sea ice melting, as illustrated by the image below showing smoke from wildfires in Canada extending over the Beaufort Sea (main image), in addition to high methane levels that are present over the Beaufort Sea (inset). 


Ocean heat is also very high and rising. Oceans on the Northern Hemisphere were 0.93°C (or 1.7°F) warmer in the most recent 12-months period (May 2015 through April 2016) than the 20th century average.

The image below shows sea ice extent as measured by the NSIDC, confirming that melting of the sea ice in 2016 is way ahead on previous years.