In this post, Sam Carana shows that the aspirational goal (agreed to in Paris) of limiting the global temperature rise to 1.5°C is quite simply, delusional. (Rolly Montpellier, Editor for BoomerWarrior).
Temperature Rise of 1.5°C by 2024?
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.
How much have temperatures risen already? In the above illustration, NASA data show that during the three-month period from September through November 2015, it was ~1°C warmer than it was in 1951-1980 (i.e the baseline).
A polynomial trend based on the data from 1880 to 2015 for these three months indicates that a temperature rise of 1.5°C compared to the baseline will be reached in the year 2024.
Let’s go over the calculations. The trendline shows it was ~0.3°C colder in 1900 compared to the baseline. Together with the current ~1°C rise, that implies that since 1900 there’s been a rise of 1.3°C compared to the baseline. This makes that another rise of 0.2°C by 2024, as pointed at by the trendline, would result in a joint rise in 2024 of 1.5°C compared to the baseline.
The situation is even worse than this. The Paris Agreement seeks to avoid a temperature increase of 1.5°C above pre-industrial levels. When we include temperature rises from pre-industrial levels to the year 1900, it becomes evident that we have already surpassed a rise of 1.5°C since pre-industrial levels. This is illustrated below from a recent post by Michael Mann, who adds that ~0.3°C greenhouse warming had already taken place by the year 1900.
Let’s add things up again. A rise of ~0.3°C before 1900, a further rise of 0.3°C from 1900 to the baseline (1951-1980) and a further rise of ~1°C from the baseline to date. Together that adds up to a rise of ~1.6°C from pre-industrial levels.
In other words, we have already surpassed a rise of 1.5°C from pre-industrial levels by 0.1°C. The trendline indicates that a further rise of 0.5°C will take place by the year 2030, i.e. that without comprehensive and effective action, it will be 2°C warmer than pre-industrial levels before the year 2030.
Full Wrath of Emissions on the Horizon
The full wrath of global warming is yet to come and the situation is even more threatening than pictured above, for the following reasons:
- Half of global warming has until now been masked by aerosols, particularly sulfates that are emitted when some of the dirtiest fossil fuels are burnt, such as coal and bunker oil. As we make the necessary shift to clean energy, the masking effect that comes with those emissions will disappear.
- As Ricke and Caldeira point out, the carbon dioxide that is released now will only reach its peak impact a decade from now. In other words, we have yet to experience the full wrath of the carbon dioxide emitted over the past decade.
- The biggest threat comes from temperature peaks. People in some parts of the world will be hit harder, especially during summer peaks, as discussed in the next section of this post. As temperatures rise, the intensity of such peaks will increase.
- Feedbacks such as rapid albedo changes in the Arctic and large amounts of methane abruptly released from the Arctic Ocean seafloor could dramatically accelerate the temperature rise. Furthermore, water vapor will increase by 7% for every 1°C warming. Water vapor is one of the strongest greenhouse gases, so increasing water vapor will further contribute to a non-linear temperature rise.
Worse for Northern Hemisphere
Such a temperature rise will hit some people more than others. For people living on the Northern Hemisphere, the outlook is worse than for people in the Southern Hemisphere.
NOAA data show that the November global land and ocean temperature anomaly was 0.97°C, while the 3-month global land and ocean temperature anomaly was 0.96°C. The 12-month anomaly on November 2015 on land on the Northern Hemisphere (where most people live) was 1.39°C while the trendline shows that for people living on the Northern Hemisphere, a 1.5°C rise compared to 1910-2000 could be reached as early as in 2017.
Similarly, the outlook is worse for people living in regions that are already now experiencing high temperatures during the summer peaks. With a temperature rise, the intensity of such peaks will increase.
Arctic Feedback Loops
The image below, from an earlier post, depicts the impact of feedbacks that are accelerating warming in the Arctic (NASA data up to November 2013) and their threat to cause runaway global warming. As the image shows, temperatures in the Arctic are rising faster than elsewhere in the world, but global warming threatens to catch up as feedbacks start to kick in more.
The situation obviously has deteriorated further since this image was created in November 2013.
Sea surface temperature anomalies, combined with rising temperatures of the water beneath the sea surface, are exacerbating the climate crisis. Anomalies as high as 10.3°C or 18.5°F were recorded off the east coast of North America on December 11, 2015, while on December 20, 2015, temperatures as high as 10.7°C or 51.3°F were recorded near Svalbard — an anomaly of 9.3°C or 16.7°F.
This warm water is carried by the Gulf Stream into the Arctic Ocean, threatening to unleash huge amounts of methane from its seafloor.
Methane is released over the Arctic Ocean in large amounts, and this methane is moving toward the equator as it reaches high altitudes. Methane levels have risen by an estimated average of 9 ppb or some 0.5%. Annual emissions from hydrates were estimated to amount to 99 Tg annually in a 2014 post (image below).
An additional 0.5% of methane represents an amount of some 25 Tg of methane. This comes on top of the 99 Tg of methane estimated in 2014 to be released from hydrates annually.
The situation is dire and calls for comprehensive and effective action as described at the Climate Plan.
I used this graph and did a pencil difference between 2015 and 2025. On RCP8.5 it appears about .4*C between the two different years. So it is possible within margin of error. If my inaccurate pencil estimation is any indicator, warming would have to be in worst case scenario and on the stronger side of warming.
If we turn down our emissions based on IPCC projections of RPC2.6 it would be about .2*C.
If I understand what you’re saying, the best case scenario is a .2 degree increase over the next 10 years, or .4 degree increase under a worst case scenario. Since we’re already at almost at 1.1, we will still be close to 1.5 warmer than pre-industrial levels by 2014.
Thank you for your comments.