Does Rising Methane Signal a 'Big Change’ in Climate?

Euan Nisbet, Royal Holloway University of London

Understanding Rising Methane

Since 2006, the size of the heat-trap Methane Unlike the increase in carbon dioxide in the Earth’s atmosphere, which is rising rapidly (CO2), recent increases in methane are driven by biological emissions, not by burning fossil fuels. This may be normal variation, a result of such natural climate cycles boy. Or It can signal A major change in Earth’s climate has begun.

Molecule for molecule, methane is a more potent greenhouse gas than CO2, but it lasts less than a decade in the atmosphere compared to centuries for CO2. Methane emissions threaten humanity’s ability to limit warming to relatively safe levels. More worryingly, the rate at which methane is increasing in the atmosphere has recently accelerated. Something like this has happened before: sudden waves of methane marked the transition from cold ice ages to warmer glacial climates.

It was about methane 0.7 parts per million (ppm) The volume of air before humans began burning fossil fuels. Now it is Above 1.9 ppm And rising fast. About 3/5 of emissions come from fossil fuel use, agriculture, landfills and waste. The remainder is from natural sources, particularly decaying vegetation in tropical and northern wetlands.

Methane is a driver and messenger of climate change. We don’t know why it’s rising so fast now, but the pattern of growth since late 2006 resembles how methane behaved during major flips in Earth’s climate in the distant past.

Methane Record: 2006 to Present

In late 2006, an unexpected increase in atmospheric methane started rising. Methane rose rapidly in the 19th and 20th centuries but plateaued in the late 1990s. Emissions from fossil fuels, particularly gas fields and coal mines, have increased.

Imagine accelerating a car with your foot flat on the bottom. The car accelerates, but eventually the air resistance equals the mechanical force and the car hits maximum speed. By 1999, methane appeared to have reached a similar balance between its sources and sinks. Then in late 2006, methane levels in the air He climbed quickly. Even more unexpected is the rate of growth after five years Accelerated again. In the 2020s, the growth rate is still faster than the peak of gas industry leaks. In the 1980s.

Today’s growth seems to be driven New emissions from Wetlandsespecially near the equator but possibly also from Canada (Beavers methane plants No pull A large amount of plant material ponds they made) and Siberia. This is a result of climate change: increased precipitation makes wetlands wetter and larger, while rising temperatures increase plant growth, providing more decomposition and more methane. There may also be emissions from large livestock in tropical Africa, India and Brazil rising and rotting waste Terrain Major sources are also near megacities like Delhi.

Methane explains the increase

Climate decision

In the past A few million yearsEarth has climate Flipped over and over again Between long, cold glacial periods, ice sheets covering northern Europe and Canada and short warm inter-glacial periods.

At the end of each ice age, the Earth’s surface warmed by several degrees Celsius over a few thousand years. Recorded in air bubbles in ice caps, sharply rising methane concentrations are the bellwethers of these larger climate-warming events. Sudden, sharp rises in atmospheric methane can occur with each flip from glacial to interglacial climates. Expanding tropical wetlands.

These are called major climate overturns that end each ice age stops. Each contains a Roman numeral that begins less than the modern era from Termination IX to Termination IA, which occurred about 800,000 years ago. 12,000 years ago. For example, around 131,000 years ago During End II, the British climate suddenly changed from glaciers in the Cotswolds to what is now the hippopotamus in Trafalgar Square.

The full results will take several thousand years to complete, but many include the creeping onset of warming, followed by a very rapid phase of climate change. A century or less, followed by a long, slow period in which large ice sheets finally melt. During the sudden phase of the great change that brought about the modern climate, Greenland’s temperature rose by about 10 degrees Celsius. A few decades. During these sudden stages, methane rises very steeply.

Does Rising Methane Mark an End Event?

Methane fluctuated widely in pre-industrial times. But its increasingly rapid growth since 2006 is comparable to methane records from the early years of abrupt phases of past termination events, such as those that warmed Greenland so dramatically. 12,000 years ago.

There is already a lot of evidence that the climate is changing. Atlantic ocean currents SlowlyTropical climate regions expandsThere are far north and far south Heats up fast, Ocean heat breaking records and Extreme weather It is becoming routine.

At the end of the glaciation, the entire climate system is rearranged. In the past, this drove the Earth out of a stable Ice Age climate and into warmer glaciers. But we are already on a warm glacier. What comes next is hard to imagine: Arctic sea ice loss in summer, thinning or partial collapse of ice sheets in Greenland and West Antarctica, realignment of Atlantic ocean currents, and poleward expansion of tropical weather circulation patterns. The consequences for the biosphere in general and food production in parts of South and East Asia and Africa in particular will be significant.

How to prevent methane build-up

There is only so much we can do urgently Stop methane build-up: Containment of spills in oil and gas industry, land cover, reduction of crop-waste burning. Firing the methane messenger won’t stop climate change, which is driven primarily by CO2 emissions, but it will help.

The Roman numerals IX through I refer to past climate changes. The Roman numeral is not zero, but any future outcome-scale change will be different, a temperature step from our current glacial climate to some new future even warmer. The methane signal is still unclear, but the question remains: is there The result is null started?

Euan NisbetProfessor of Earth Sciences, Royal Holloway University of London.

This article has been republished Conversation Under Creative Commons License. Read on Original article.

Bottom line: Professor Euan Nisbett says the recent steep gradient in methane levels may signal an end-to-end event on Earth as climate systems reset.

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