Before a detailed look at the alarming news from the Arctic, We begin with the latest on warming from the European Environment Agency, which concludes:
- According to different observational records of global average annual near-surface (land and ocean) temperature, the last decade (2008–2017) was 0.89 °C to 0.93 °C warmer than the pre-industrial average, which makes it the warmest decade on record. Of the 17 warmest years on record, 16 have occurred since 2000. The year 2017 was one of the world’s three warmest years on record together with the years 2016 and 2015.
- The average annual temperature for the European land area for the last decade (2008–2017) was between 1.6 °C and 1.7 °C above the pre-industrial level, which makes it the warmest decade on record. In Europe, 2017 was colder than the previous 3 years.
- Climate models project further increases in global average temperature over the 21st century (for the period 2081–2100 relative to 1986–2005) of between 0.3 °C and 1.7 °C for the lowest emissions scenario (RCP2.6) and between 2.6 °C and 4.8 °C for the highest emissions scenario (RCP8.5).
- All UNFCCC [United Nations Framework Convention on Climate Change] member countries have agreed on the long-term goal of keeping the increase in global average temperature to well below 2 °C compared with pre-industrial levels and have agreed to aim to limit the increase to 1.5 °C. For the three highest of the four RCPs, the global average temperature increase is projected to exceed 2 °C compared with pre-industrial levels by 2050.
- Annual average land temperature over Europe is projected to increase by the end of this century (2071–2100 relative to 1971–2000) in the range of 1.0 °C to 4.5 °C under RCP4.5 and 2.5 °C to 5.5 °C under RCP8.5, which is more than the projected global average increase. The strongest warming is projected across north-eastern Europe and Scandinavia in winter and southern Europe in summer.
- The number of warm days (those exceeding the 90th percentile threshold of a baseline period) have doubled between 1960 and 2017 across the European land area.
Europe has experienced several extreme heat waves since 2000 (2003, 2006, 2007, 2010, 2014, 2015 and 2017). Under a high emissions scenario (RCP8.5), extreme heat waves as strong as these or even stronger are projected to occur as often as every two years in the second half of the 21st century. In southern Europe, they are projected to be particularly strong.
The first graphic from the report tracks the soaring temperatures sparked by the Industrial Revolution [click on the images to enlarge]:
The second, a series of maps, tracks projected temperature rises under a regime in which emissions caps are imposed to a significant degree [upper maps], while the lower maps reflect higher levels under the regime so beloved by the White House:
Whichever regime prevails, temperatures, occasions, heat-associated deaths, extinctions, and more are all set to rise, with Home Sapiens able only to mitigate the degree.
Are we approaching a critical threshold?
Threshold events in which dramatic changes are triggered by small shifts in existing conditions. Water is water until it hits the freezing point, and ice stays ice until its temperature reaches the same point. What was liquid becomes solid, what was solid becomes liquid.
We also know from everyday experience that cold shows living things down, while freezing generally brings them to a halt.
The threshold at which ice melts is shaping up to have major impacts on global warming, both through the release of trapped methane in the Arctic permafrost [about which we’ve posted extensively] and for the generation of new greenhouse gases in the form of carbon dioxide generated by microbes now able to digest dead organic matter at above-freezing temperatures.
The findings come from Pacific Northwest National Laboratory, a highsecurity facility in Richland, Washington, run by the Department of Energy and focusing on terrorism, nuclear proliferation, cyberwar, energy independence, and climate change.
Unlike the White House, th national security establishment sees climate change as a real threat, so much so that it’s a matter of national security.
The vast reservoir of carbon stored beneath our feet is entering Earth’s atmosphere at an increasing rate, most likely as a result of warming temperatures, suggest observations collected from a variety of the Earth’s many ecosystems.
Blame microbes and how they react to warmer temperatures. Their food of choice – nature’s detritus like dead leaves and fallen trees – contains carbon. When bacteria chew on decaying leaves and fungi chow down on dead plants, they convert that storehouse of carbon into carbon dioxide that enters the atmosphere.
In a study published August 2 in Nature, scientists show that this process is speeding up as Earth warms and is happening faster than plants are taking in carbon through photosynthesis. The team found that the rate at which microbes are transferring carbon from soil to the atmosphere has increased 1.2 percent over a 25-year time period, from 1990 through 2014.
While that may not seem like a big change, such an increase on a global scale, in a relatively short period of time in Earth history, is massive. The finding, based on thousands of observations made by scientists at hundreds of sites around the globe, is consistent with the predictions that scientists have made about how Earth might respond to warmer temperatures.
“It’s important to note that this is a finding based on observations in the real world. This is not a tightly controlled lab experiment,” said first author Ben Bond-Lamberty of the Joint Global Change Research Institute, a partnership between the Department of Energy’s Pacific Northwest National Laboratory and the University of Maryland.
“Soils around the globe are responding to a warming climate, which in turn can convert more carbon into carbon dioxide which enters the atmosphere. Depending on how other components of the carbon cycle might respond due to climate warming, these soil changes can potentially contribute to even higher temperatures due to a feedback loop,” he added.
Globally, soil holds about twice as much carbon as Earth’s atmosphere. In a forest where stored carbon is manifest in the trees above, even more carbon resides unseen underfoot. The fate of that carbon will have a big impact on our planet. Will it remain sequestered in the soil or will it enter the atmosphere as carbon dioxide, further warming the planet?
To address the question, the team relied heavily on two global science networks as well as a variety of satellite observations. The Global Soil Respiration Database includes data on soil respiration from more than 1,500 studies around the globe. And FLUXNET draws data from more than 500 towers around the world that record information about temperature, rainfall and other factors.
“Most studies that address this question look at one individual site which we understand very well,” said author Vanessa Bailey, a soil scientist. “This study asks the question on a global scale. We’re talking about a huge quantity of carbon. Microbes exert an outsize influence on the world that is very hard to measure on such a large scale.”
The study focused on a phenomenon known as “soil respiration,” which describes how microbes and plants in the soil take in substances like carbon to survive, then give off carbon dioxide. Soils don’t exactly breathe, but as plants and microbes in soil take in carbon as food, they convert some of it to other gases which they give off – much like we do when we breathe.
Scientists have known that as temperatures rise, soil respiration increases. Bond-Lamberty’s team sought to compare the roles of the two main contributors, increased plant growth and microbial action.
The team discovered a growing role for microbes, whose action is outstripping the ability of plants to absorb carbon. In the 25-year span of the study, the proportion of soil respiration that is due to microbes increased from 54 to 63 percent. Warmer temperatures can prompt more microbial action, potentially resulting in more carbon being released from carbon pools on land into the air.
“We know with high precision that global temperatures have risen,” said Bond-Lamberty. “We’d expect that to stimulate microbes to be more active. And that is precisely what we’ve detected. Land is thought to be a robust sink of carbon overall, but with rising soil respiration rates, you won’t have an intact land carbon sink forever.”