How Much Warming Have Humans Caused?

How much did temperatures rise?

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, temperatures over the past half year were 1.05°C (1.89°F) higher than this baseline, as shown by the NASA map in the left panel of the image below. As the map in the right panel of the image below shows, when compared to 1890-1910, temperatures have risen by 1.48°C (or 2.664°F).

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 within a decade and more than 2°C soon thereafter.

Historical Temperatures

To calculate by how much warming humans have caused since pre-industrial times, we need to go back further than 1900. The graph below shows that carbon dioxide concentrations have gone up and down between roughly 180 ppm and 280 ppm over the past 800,000 years and did recently reach a peak of 411 ppm (peak hourly average on May 11, 2016).

The graph below, from an earlier post, shows how in the past, over the past 420,000 years, temperatures (and levels of CO2 and CH4) have gone up and down by some 10°C, in line with the Milankovitch cycles.

Historically, carbon dioxide rises of 100 ppm have gone hand in hand with temperature rises of some 10°C. The recent rise in carbon dioxide concentrations is a 131 ppm rise (from some 280 ppm to 411 ppm). The rise in methane concentrations is even steeper. Could we therefore expect a temperature rise of more than 10°C to happen, and if so how soon could this eventuate? As described below, warming caused by humans could result in a temperature rise of more than 10°C (18°F) within a decade.

The graph on the right, created by Jos Hagelaars, shows that, during the most current cycle, temperatures reached a peak some 7000 years ago (in the blue part of the graph).

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) over the period suggest a fall of more than 0.7°C.

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. That may suggest that humans have caused a total of 1.45°C warming.

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. 

Temperatures before 1900 were already higher than what they would have been had humans caused no warming. 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.

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, so they are only indicative for the total rise for the year 2016. Nonetheless, when taking into account warming caused by people before 1900, the year 2016 looks set to 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 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.

At the same time, part of global warming caused by people is currently masked due the aerosol emissions (∆A). Such aerosol emissions result from mainly 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) warming caused by humans is the sum of these two, i.e. ∆E + ∆A, and the sum could be as high as 3°C or even more than 5°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 + ∆A together, i.e. ∆F could alone cause a temperature rise of more than 5°C within a decade.

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

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


Links

- Methane Erupting From East Siberian Arctic Shelf
http://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
http://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
http://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
http://arctic-news.blogspot.com/2016/03/february-temperature.html

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

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.

Here's an animation comparing sea surface temperatures of the North Atlantic between May 25, 2015, and May 25, 2016.

Arctic sea ice extent was 10.7 million km² on May 25, 2016, 1.1 million km² less than it was on May 25, 2012, as the update below shows.

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

Further Confirmation Of Arctic Sea Ice Dramatic Fall

Since early April, 2016, there have been problems with the sensor on the F-17 satellite that provided the data for many Arctic sea ice images. On April 12, NSIDC issued a notice that it had suspended the provision of sea ice updates. On May 6, NSIDC announced that it had completed the shift to another satellite. The red dotted line in the image below shows data from the F-18 satellite from April 1 to May 15, 2016.

The JAXA site also provides sea ice extent images, obtaining data from a Japanese satellite. They show that Arctic sea ice extent on May 15, 2016 was 11,262,361 square km, 1.11 million square km less than it was on May 15, 2012.

The Cryosphere Today is still using data from the F17 satellite, showing some weird spikes. Albert Kallio has taken a recent image and removed faulty spikes, resulting in the image below showing sea ice area up to May 3, 2016.

[ yellow line is 2016, red line is 2015 ]

Importantly, above image confirms that Arctic sea ice in 2016 has indeed been very low, if not at its lowest for the time of the year. Especially since April 2016, sea ice has fallen far below anything we've seen in earlier years. Below, Albert elaborates on comparing data.

by Albert Kallio‎ REPAIRED USA (F-17) SATELLITE DATA SHOWS RECORD SMALL SEA ICE AREA IN MAY 2016 AGREEING JAPANESE (JAXA) DATA A corrected Special Sensor Microwave Imager and Sounder (SSMIS) data set on the Defense Meteorological Satellite Program (DMSP) F-17 satellite that provides passive microwave brightness temperatures (and derived Arctic and Antarctic sea ice products) has been corrected here for the system instrumentation error. This agrees with the Japanese JAXA curve, and has been accomplished by removal of the uncharacteristic upward 'ice growth' spikes by linear intrapolation of the corrupt data points. This reinforces the JAXA data that shows the Northern Hemisphere sea ice area is seasonally at new record low which has continued in May 2016. Smoothened F-17 curve agrees with the Japanese JAXA satellite curve. The reconciliation of the two has been accomplished by removal of the uncharacteristic upward spikes by linear intrapolation of the corrupt days' data points which incorrectly showed immense sea ice area growth in the middle of spring melt season. This reinforces the JAXA data that shows the sea ice area is seasonally at record lows. Therefore, media who are citing recent F-17 satellite sea ice area figures are intentionally distorting the facts with their claims of the Northern Hemisphere having a record sea ice area for this time of season - whereas in reality - the exact opposite has been happening.

Arctic sea ice is in a bad shape and looks set to deteriorate even further, for a number of reasons.

The year 2016 is an El Niño year, as illustrated by the 51.1°C (124.1 °F) forecast for May 22, 2016, over the Indus Valley in Pakistan (see image right).

Insolation during the months June and July is higher in the Arctic than anywhere else on Earth. Greenhouse gases are at record high levels: CO2 was 408.2 ppm on May 12, 2016, and methane levels are high and rising, especially over the Arctic.

Ocean heat is also very high and rising. The image below shows that 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 situation is further illustrated by the image below, using the NOAA data with a trendline added that points at a rise of 3°C (5.4°F) before the year 2040.

Chances are that Arctic sea ice will be largely gone by September 2016. As the ice declines, ever more sunlight gets absorbed by the Arctic Ocean. This is one out of numerous feedbacks that are hitting the Arctic. The danger is that, as these feedbacks start to kick in more, heat will reach the seafloor of the Arctic Ocean and trigger methane to be released in huge quantities from the Arctic Ocean seabed.

Recently, an abrupt methane release from the Arctic Ocean seafloor did enter the atmosphere over the East Siberian Sea, showing up with levels as high as 2578 ppb (at 586 mb on May 15, 2016, pm, see image below). Such abrupt releases are indications that methane hydrates are destabilizing and are warnings that climate catastrophe is waiting to happen.

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

Arctic Sea Ice gone by September 2016?

Arctic sea ice extent is very low, much lower than it was in other years at this time of year. On May 11, 2016, Arctic sea ice extent was 12.328 million square km, according to the National Snow and Ice Data Center (NSIDC), while JAXA's figure for extent on May 11, 2016, was only 11.57 million square km.

[ based in image from JAXA ]

JAXA figures show that Arctic sea ice extent on May 9, 2016, was 11.68 million square km, more than 18 days ahead on 2012 and 1.1 million square km smaller than it was on May 9, 2012.

The image on the right compares the Beaufort Sea and the northern part of Alaska between May 9, 2012 and May 9, 2016. As the image illustrates, there now is a lot less ice and snow cover than there was on 2012.

The situation looks set to deteriorate further over the coming months. The image below shows temperature forecast to reach anomalies as high as 5.19°C or 9.34°F for the Arctic as a whole (forecast for May 19, 2016, 0300 UTC), with temperature anomalies at the top end of the scale forecast for Alaska and eastern Siberia.

These temperature anomalies go hand in hand with a very wavy jet stream, as illustrated by the image on the right, showing loops extending all the way over the Arctic Ocean (in particular over the Beaufort Sea), taking along warm air in their path.

At the same time, the jet stream can extend far south at other places, making that cold air is moving south, out of the Arctic.

The result is a rapidly warming Arctic, which in turn makes the jet stream even more wavier, as one out of numerous feedbacks that are all  hitting the Arctic at the same time.

The image below compares sea ice thickness between May 13, 2012, and May 13, 2016.

The image on the right shows that sea surface temperatures near Svalbard were as high as 55°F (12.8°C) on May 11, 2016, an anomaly of 21.2°F (11.8°C) from 1981-2011. In other words, the temperature of the sea surface was 1°C in that spot from 1981 to 2011, and now this spot is 11.8°C warmer.

The image below compares sea surface temperature anomalies from 1961-1990 between May 12, 2015, and May 12, 2016.

Sea surface temperatures in the Arctic Ocean are higher than they used to be, in particular in the Bering Strait, the Beaufort Sea, in Baffin Bay and the Kara Sea.

[ click on images to enlarge ]

In summary, Arctic sea ice is in a very bad shape, while ocean heat is very high and rising. Greenhouse gas levels are at record high levels, as discussed in an earlier post and as further illustrated by the image below.

The image below shows that, over the past 365 days, warming over the Arctic have been much stronger than over the rest of the world. Air temperature anomalies of more than 2.5°C (4.5°F) show up over most of the Arctic Ocean. Furthermore, as discussed above, high temperatures are forecast to hit the Arctic over the next week.

From November 2015 to April 2016, global temperatures over land and oceans were 1.48°C (or 2.664°F) higher than in 1890-1910 (left map of the image below). On land, it was 1.99°C (or 3.582°F) warmer (right map of the image below).

[ also see comments ]

Since some 0.3°C (0.54°F) greenhouse warming had already taken place by the year 1900, warming was well above the 1.5°C (or 2.7°F) guardrail the Paris Agreement had pledged wouldn't be crossed.

Given the above, chances are that the sea ice will be largely gone by September 2016.

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

Wildfire Danger Increasing

Wildfires are starting to break out in British Columbia, Canada. The wildfire on the image below started on May 1, 2016 (hat tip to Hubert Bułgajewski‎).

The coordinates of the wildfire are in the bottom left corner of above map. They show a location where, on May 3, 2016, it was 26.0°C (or 78.8°F). At a nearby location, it was 27.6°C (or 81.8°F) on May 3, 2016. Both locations are indicated on the map on the right.

These locations are on the path followed by the Mackenzie River, which ends up in the Arctic Ocean. Wildfires aggravate heat waves as they blacken the soil with soot. As the Mackenzie River heats up, it will bring warmer water into the Arctic Ocean where this will speed up melting of the sea ice.

Moreover, winds can carry soot high up into the Arctic, where it can settle on the sea ice and darken the surface, which will make that more sunlight gets absorbed, rather than reflected back into space as before.

The danger of wildfires increases as temperatures rise. The image on the right show that temperatures in this area on May 3, 2016 (00:00 UTC) were at the top end of the scale, i.e. 20°C or 36°F warmer than 1979-2000 temperatures.

Extreme weather is becoming increasingly common, as changes are taking place to the jet stream. As the Arctic warms up more rapidly than the rest of the world, the temperature difference between the Equator and the North Pole decreases, which in turn weakens the speed at which the north polar jet stream circumnavigates the globe.

This is illustrated by the wavy patterns of the jet stream in the image on the right, showing the situation on May 3, 2016 (00:00 UTC), with a loop bringing warm air high up into North America and into the Arctic.

In conclusion, warm air reaching high latitudes is causing the sea ice to melt in a number of ways:

• Warm air makes the ice melt directly. 
• Warmer water in rivers warms up the Arctic Ocean. 
• Wildfires blacken land and sea ice, causing more sunlight to be absorbed, rather than reflected back into space as before.  

[ click on images to enlarge ]

The situation doesn't appear to be improving soon, as illustrated by the image on the right. Following the record high temperatures that hit the world earlier this year, the outlook for the sea ice looks bleak.

Further decline of the snow and ice cover in the Arctic looks set to make a number of feedbacks kick in stronger, with methane releases from the seafloor of the Arctic Ocean looming as a huge danger.

NSIDC scientist Andrew Slater has created the chart below of freezing degree days in 2016 compared to other years at Latitude 80°N. See Andrew's website and this page for more on this.

Below is a comparison of temperatures and emissions for the two locations discussed above. Such fires are becoming increasingly common as temperatures rise, and they can cause release of huge amounts of carbon dioxide, carbon monoxide, methane, sulfur dioxide, soot, etc.

May 3, 2016, at a location north of Fort St John, British Columbia, Canada.

May 4, 2016, near Fort McMurray, Alberta, Canada.

The video below shows methane levels (in parts per billion or ppb) on May 3, 2016, pm, starting at 44,690 ft or 13,621 m and coming down to 5,095 ft or 1,553 m altitude. In magenta-colored areas, methane is above 1950 ppb.

In the video below, Paul Beckwith discusses the situation.

Wildfires are also devastating other parts of the Earth. Below is an image showing wildfires over the Amur River on May 7, 2016.

The image below shows carbon monoxide levels over the Amur River as high as 22,480 ppb on May 9, 2016. Hat tip to Grofu Antoniu for pointing at the CO levels. According to this Sputniknews report, a state of emergency was declared in the Amur Region as fires stretched across 12,200 acres.

The video below shows carbon monoxide emissions in eastern Asia from May 1 to May 26, 2016.

Meanwhile, the National Snow and Ice Data Center (NSIDC) has resumed daily sea ice extent updates with provisional data. The image below is dated May 5, 2016, check here for updates.

As illustrated by the image below, from JAXA, sea ice extent on May 6, 2016, was under 12 million square km, more than 15 days ahead on extent in the year 2012, which was 12 million square km on May 21, 2012.

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

Malcolm Light comments: Most natural processes on the Earth are run by convection including plate tectonics that moves the continental and oceanic plates across the surface of the planet. Mother Earth has been able to hold its atmospheric temperature within certain limits and maintain an ocean for more than 3 billion years because each time there was a build up of carbon dioxide in the atmosphere which produced a global fever, Mother Earth it eliminated the living creatures with a massive Arctic methane firestorm that fried them alive. This giant Arctic methane firestorm is a natural antibiotic the Earth uses to rid itself of those creatures that have overproduced carbon dioxide and caused a global fever. Essentially mankind has again caused a massive build up of fossil fuel carbon dioxide in the atmosphere and Mother Earth has already started to respond with the predicted massive Arctic methane blow out (since 2010) which will lead to an Earth engulfing firestorm in 5 to 8 years. The giant fires in the Fort McMurray region are a result of atmospheric methane induced heating of the Arctic and 93.5% global warming of the oceans that has generated a massive El Nino event this year. Hot winds moving away from these high pressure areas have generated high temperatures and massive fires in Alberta which is a giant fever spot on Earth where mankind has produced the maximum amount of dirty fossil fuel extraction and pollution in Canada. Mother Earth will continue to respond more vigorously with her Arctic methane antibiotic to eliminate the humans from her system as we represent nothing more to her than a larger version of an influenza virus which has seriously retarded her oceanic and atmospheric temperature range functioning systems. If we do not immediately stop fossil fuel extraction worldwide and control the Arctic methane emission sites we will all be stardust before a decade is past.

Related

- The Threat of Wildfires in the North
http://arctic-news.blogspot.com/2013/06/the-threat-of-wildfires-in-the-north.html

- Smoke Blankets North America

http://arctic-news.blogspot.com/2014/07/smoke-blankets-north-america.html

- Wildfires even more damaging
http://arctic-news.blogspot.com/2013/07/wildfires-even-more-damaging.html

- Wildfires in Canada affect the Arctic
http://arctic-news.blogspot.com/2013/07/wildfires-in-canada-affect-the-arctic.html