13 March, 2016
The February 2016 land and ocean temperature anomaly was 1.35°C (2.43°F) above the average temperature in the period from 1951 to 1980, as above image shows (Robinson projection).
On land, it was 1.68°C (3.02°F) warmer in February 2016, compared to 1951-1980, as the image below shows (polar projection).
The image below combines the above two figures in two graphs, showing temperature anomalies over the past two decades.
At the Paris Agreement, nations committed to strengthen the global response to the threat of climate change by holding 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.
To see how much temperatures have risen compared to pre-industrial levels, a comparison with the period 1951-1980 does not give the full picture. The image below compares the February 2016 temperatures with the period from 1890 to 1910, again for land only.
Since temperatures had already risen by ~0.3°C (0.54°F) before 1900, the total temperature rise on land in February 2016 thus is 2.6°C (4.68°F) compared to the start of the industrial revolution.
There are a number of elements that determine how much the total temperature rise on land will be, say, a decade from now:
Rise 1900-2016: In February 2016, it was 2.3°C (4.14°F) warmer on land than it was in 1890-1910.
Rise before 1900: Before 1900, temperature had already risen by ~0.3°C (0.54°F), as Dr. Michael Mann points out (see earlier post).
Rise 2016-2026: In 2015, mean global carbon dioxide grew by 3.09 ppm, more than in any year since the record started in 1959, prompting an earlier post to add a polynomial trendline that points at a growth of 5 ppm by 2026 (a decade from now). If levels of carbon dioxide and further greenhouse gases do keep rising, there will additional warming over the next ten years. Even with dramatic cuts in carbon dioxide emissions, temperatures will keep rising, as maximum warming occurs about one decade after a carbon dioxide emission, so the full wrath of the carbon dioxide emissions over the past ten years is still to come.
Removal of aerosols: With dramatic cuts in emissions, there will also be a dramatic fall in aerosols that currently mask the full warming of greenhouse gases. From 1850 to 2010, anthropogenic aerosols brought about a decrease of ∼2.53 K, says a recent paper. In addition, people will have emitted a lot more aerosols since 2010, so the current masking effect of aerosols will be even higher.
Albedo change: 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, calculated Professor Peter Wadhams in 2012.
Methane eruptions from the seafloor: ". . . we consider release of up to 50 Gt of predicted amount of hydrate storage as highly possible for abrupt release at any time," Dr. Natalia Shakhova et al. wrote in a paper presented at EGU General Assembly 2008. Authors found that such a release would cause 1.3°C warming by 2100. Note that such warming from an extra 50 Gt of methane seems conservative when considering that there now is only some 5 Gt of methane in the atmosphere, and over a period of ten years this 5 Gt is already responsible for more warming than all the carbon dioxide emitted by people since the start of the industrial revolution.
Water vapor feedback: "Water vapour feedback acting alone approximately doubles the warming from what it would be for fixed water vapour. Furthermore, water vapour feedback acts to amplify other feedbacks in models, such as cloud feedback and ice albedo feedback. If cloud feedback is strongly positive, the water vapour feedback can lead to 3.5 times as much warming as would be the case if water vapour concentration were held fixed", according to the IPCC.
The image below puts these elements together in two scenarios, one with a relatively low temperature rise of 3.9°C (7.02°F) and another one with a relatively high temperature rise of 10.4°C (18.72°F).
Note that the above scenarios assume that no geoengineering will take place.
The situation is dire and calls for comprehensive and effective action, as described in the Climate Plan.