Thursday, 14 January 2016

Greenhouse gas levels and temperatures keep rising

At the Paris Agreement, nations pledged to cut emissions and avoid dangerous temperature rises. Yet, the rise in greenhouse gas levels and temperatures appears to be accelerating.

Record growth of carbon dioxide levels at Mauna Loa

Annual mean carbon dioxide level measured at Mauna Loa, Hawaii, grew by 3.17 ppm (parts per million) in 2015, a higher growth rate than in any year since the record started in 1959.

As above image shows, a polynomial trendline added to the data points at a carbon dioxide growth rate of 4 ppm by the year 2024 and 5 ppm by the year 2028. 

At the start of the Industrial Revolution, the carbon dioxide level in the atmosphere was about 280 ppm. On January 11, 2016, as above image shows, carbon dioxide level at Mauna Loa, Hawaii, was 402.1 ppm. That's some 143% times what the upper level of carbon dioxide was in pre-industrial times over at least the past 400,000 years, as the image further below illustrates.

At higher northern latitudes, carbon dioxide levels are higher than elsewhere on Earth, as illustrated by above image. These high greenhouse gases contribute to accelerated warming of the Arctic. 

Methane levels rising even faster than CO2 levels, especially over Arctic Ocean

Historically, methane levels have been moving up and down between a window of 300 and 700 ppb. In modern times, methane levels have been rising even more rapidly than carbon dioxide levels, as illustrated by the image below, from an earlier post.

As above image illustrates, the mean level of 1839 ppb that was reached on September 7, 2014, is some 263% of the ~700 ppb that historically was methane's upper level.

The image below, from an earlier post, shows the available World Meteorological Organisation (WMO) annual means, i.e. from 1984 through to 2014, with added polynomial trendline based on these data. The square marks a high mean 2015 level, from NOAA's MetOp-2 satellite images, and it is added for comparison, so it does not influence the trendline, yet it does illustrate the direction of rise of methane levels and the threat that global mean methane levels will double well before the year 2040.

Recently, some very high peak levels have been recorded, including a reading of 2745 ppb on January 2, 2016, and a reading of 2963 ppb on January 8, 2016, shown below.

These high readings illustrate the danger that, as warmer water reaches the seafloor of the Arctic Ocean, it will increasingly destabilize sediments that can contain huge amounts of methane in the form of free gas and hydrates. Images associated with these high readings show the presence of high methane levels over the Arctic Ocean, indicating that these high peaks originate from the Arctic ocean and that sediments at the seafloor of the Arctic Ocean are destabilizing. The danger is that these peaks will be followed up by even stronger abrupt releases from the seafloor of the Arctic Ocean, as water temperatures keep rising.

Rising temperatures

Global mean temperature in 2015 was 0.87°C (~1.6°F) higher than in 1951-1980. 

Above image shows NASA data with a polynomial trendline added that points at a 2015 temperature that is more than 1.1°C (~2.03°F) higher than it was in 1900.

The image on the right shows that it was 1.17°C warmer in 2015 than it was in the period 1890-1910.

Additionally, some 0.3°C warming had already taken place by the year 1900, as discussed in an earlier post.

Together, that makes that 2015 temperatures were 1.47°C above pre-industrial levels.

Furthermore, temperatures did rise steeply over the course of the year 2015.

By the end of the year 2015, the temperature rise was even stronger than the average for 2015 would indicate, as illustrated by the image on the right.

It is now 2016 and temperatures are still rising. In other words, it now is more than 1.5°C or 2.7°F warmer than in pre-industrial times. In conclusion, we have already crossed the 1.5°C guardrail that the Paris Agreement had pledged to try and limit global warming to. 

What is the prognosis for the temperature rise from here onward? The current El Niño is expected to continue well into 2016. Even if the El Niño slows down, it will by then likely have contributed to huge losses of snow and ice cover, including sea ice melt in the Arctic. The resulting albedo changes alone may well have an even stronger warming effect than the El Niño, while there are further feedbacks such as disruption of the jet stream and methane eruptions from the seafloor of the Arctic Ocean.

The image below shows that, when that same trendline featuring in above graph is extended into the future, it points at a 2°C or 3.6°F global temperature anomaly rise before the year 2030, a rise of about 4°C or 7.2°F by 2040, and a 10°C or 18°F rise before the year 2060. That would be a rise compared to the period 1951-1980, i.e. warming compared to pre-industrial levels would be even more severe.

Three points are important to help more fully grasp the predicament we are in:
  1. At higher latitudes of the Northern Hemisphere, temperatures are rising faster than globally, as illustrated by above image that shows that a 10°C rise could hit the Arctic by 2030. 
  2. Summer peaks will be even more devastating than annual averages. 
  3. The rise of temperatures on land will be steeper than the rise in the combined land-ocean temperatures, as illustrated by the image below that shows that a 3°C rise on land could occur well before the year 2030.  

Comprehensive and effective action needed

As greenhouse gases and temperatures keep rising, the heat will be felt earliest and most severely on land, during the northern summer and in the Arctic.

One big danger is that soil that was previously frozen will become exposed and will start releasing huge amounts of carbon, in the form of carbon dioxide or methane.

Furthermore, boreal forest, tundra and peats bogs are at risk of firestorms that will also come with huge amounts of emissions.

All this will make the rise in temperature speed up even more, with much of the soot from firestorms in Siberia settling on the Himalaya Tibetan plateau, melting the glaciers there and causing short-term flooding followed by rapid decrease of the flow of ten of Asia’s largest river systems that originate there, with more than a billion people’s livelihoods depending on the continued flow of this water.

Again, the reason why temperatures look set to rise so abruptly and dramatically in the Arctic is feedbacks, as discussed as the feedbacks page. The biggest danger that comes with these rapidly rising temperatures in the Arctic is that large methane eruptions from the seafloor of the Arctic Ocean will further heat up the atmosphere, at first in hotspots over the Arctic, and eventually around the globe, while also causing huge temperature swings and extreme weather events, further contributing to increasing depletion of fresh water and food supply.

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

Below is an image by Malcolm Light, which updates an image that appeared in an earlier post

Annual mean carbon dioxide level measured at Mauna Loa, Hawaii, grew by 3.17 ppm (parts per million) in 2015, a higher...
Posted by Sam Carana on Thursday, January 14, 2016


Greenhouse gas levels and temperatures keep rising
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