Latest greenhouse gas stats show COVID impact and challenges ahead

Brace yourself for some messy science reporting in the days ahead. On October 26, the World Meteorological Organization (WMO) released its Greenhouse Gas Bulletin, a summary of where we stand with atmospheric levels of carbon dioxide, methane, and nitrous oxide. WMO pulled no punches with its presser headline, “More bad news for the planet: greenhouse gas levels hit new highs”. With the UN’s climate change conference, COP27, slated for November 6 to 18 in Sharm el-Sheikh, Egypt, there’s logic to such grim language: to focus our attention, and to encourage stronger political action. When UN Environment releases a separate Emissions Gap Report on October 27, we can expect to see the same.

The only problem is that, in a world struggling with scientific literacy, key details stand to be lost (or worse, exploited for denialism) in this framing. WMO’s latest bulletin is noteworthy, because it does an excellent job outlining what we know and don’t know with respect to these greenhouse gases. However, media reports that simply present them as at “record highs” will do readers a disservice.

That’s because these latest stats show some real puzzles scientists are still working through. Yes, capping CO2 remains our most important concern, because its accumulation will affect the climate for millennia, by activating long term impact cycles through polar ice loss and rising sea levels. And as WMO notes, we absolutely see reason for concern with respect to ongoing human impact here, since

[a]tmospheric CO2 reached 149% of the pre-industrial level in 2021, primarily because of emissions from the combustion of fossil fuels and cement production. According to the International Energy Agency, global CO2 emissions from energy combustion and industrial processes rebounded to 36.3 GtCO2 in 2021, up 6% from 34.2 GtCO2 in 2020, during which emissions were reduced with respect to the levels of the previous year due to COVID-19 restrictions.

Page 6, WMO Greenhouse Gas Bulletin, October 26

In short: surprise, surprise—we didn’t do enough to transition our economy during the early-pandemic industry slowdowns, and we now have the same steep hill to climb to reach key international climate-change mitigation targets.

However, the bulk of the report’s findings grapple with the complexity of measuring and sourcing methane emissions, which had the largest within-year increases in 2020 and 2021 since monitoring began in the 1980s. Methane is complicated: it’s both 25 times as powerful as CO2 at trapping heat in the atmosphere, and decays far faster, at a half life of around nine years. This means that, even though it’s the second-most important greenhouse gas, and can do a lot of damage in a short period, its accumulation can also be halted and even reduced within our lifetimes. The trick is figuring out what’s causing the serious recent uptick in methane emissions—and that’s where the impact of these figures gets messy.

We know that methane is emitted by two general sources: natural, and anthropogenic (a category that includes, say, livestock emissions because they’re tied to human industry). In the latter category, the fossil fuel industry alone accounts for over 20% of global emissions, so reducing its role in human activity will markedly improve both methane and CO2 figures.

But in the former category, we also have the possibility of La Niña, a storm system that started up again in 2020, escalating feedback loops in natural climates, like tropical wetlands. These cyclical weather events, and other interannual variabilities, have a huge impact on the state of natural methane sinks and sources.

Which is why scientific reporting takes a more cautious approach to its findings:

The main challenge of interpreting observed methane growth rate changes … is to prove which of several possible scenarios really happened. In the case of the 2020 growth rate increase, for example, the impact of COVID-19 lockdowns on atmospheric chemistry and the hydroxyl radical sink of methane may have been contributing factors. However, atmospheric sinks are unlikely to explain the large annual [methane] increase observed in 2021. The global methane budget initiative of the Global Carbon Project (GCP) plays an important role in synthesizing the information that is available from emission inventories, process-based models, and inverse models. … This is a process that takes several years, but at present, it is the only means of collecting enough information to determine the most likely explanation for the accelerating increase of atmospheric methane.

Page 5

Simply put, because methane markedly increased in both 2020 and 2021, its spikes cannot be as cleanly ascribed to a return to status quo after COVID lockdowns. And that difference matters when we talk about “record highs”, and how to use this data effectively in our advocacy for a responsible reaction to today’s climate crises.

Absolutely, WMO’s Greenhouse Gas Bulletin shows a steady climb of CO2 and nitrous oxide emissions, with the strong year-over-year increase in 2021 especially easy to connect to the reopening of sectors still too reliant on old economic models.

But what’s happening with methane is different. In the latest Scientific American, Douglas Fox writes “Antarctica’s Collapse Could Begin Even Sooner Than Anticipated” because even though the cascade effects of melting polar ice have been well-known for decades, scientists are still playing catch-up (for all their perceived catastrophism) to the actual rates of acceleration for climate change events and local feedback loops. The same may very well be happening with methane: a product of systems with so many overlapping sources and factors that we may not be able to fully document the chronology and causation of accelerating collapse until years after key tipping points.

While climate scientists work through competing explanatory models for the huge recent surge in methane, though, the rest of the world’s priorities remain clear:

• reduce anthropogenic production of greenhouse gases
• otherwise mitigate the extent of climate and environmental changes ahead
• build greater adaptability into all our human systems, to reduce the cost of climate change to life, livelihood, and existing habitats.

And of course, when it comes to sharing intel on all of this:

• pay close attention to when reports talk about rates of change versus absolute increases, over what periods of time, and with what kind of lump-sum grouping of a range of key problems, sources, and mitigating factors.

Because the underlying intention—to inform, and to stir us all into greater action—is absolutely the right one. We need COP27, and related international and local collaborations, to prioritize our management, mitigation, and movement through today’s climate crises.

But we also can’t expend our sociopolitical energies effectively, in all our respective advocacy spheres, if we’re building on fuzzy intel.