Professor Michael Mann is the climatologist whose famous hockey stick chart finally put climate denialism in the bin. He’s written a new book, Our Fragile Moment, about surviving the climate crisis. Here he explains why he remains hopeful about our future
1. Earth’s climate displays some degree of resilience
Four billion years ago, when our sun was only 70% as bright as it is today, climate models indicate that Earth should have been a frozen planet. And yet, it wasn’t. There were liquid water oceans that were teaming with primitive life (microbes).
The solution to the ‘faint young sun paradox’, first offered by the great scientist Carl Sagan, was that the greenhouse effect must have been higher back then. As the sun slowly grew brighter over the ensuing billions of years, the greenhouse effect gradually decreased, in just such a manner as to keep the planetary temperature within bounds habitable for life. Life, through the control it exerts over the global carbon cycle, played a key role in the carbon drawdown.
This self-stabilising characteristic of the Earth system relates to the Gaia hypothesis, first posed by the scientists James Lovelock and Lynn Margulis in the early 1970s. It proposes that the Earth itself acts in a manner similar to an organism, displaying a degree of resilience, as long as it’s not pushed too hard – including by us.
2. Rumours of our doom are much exaggerated
Climate doomers insist it’s too late to act. They claim we’ve triggered runaway warming due to a putative, unstoppable release of methane escaping into the atmosphere as the Arctic permafrost melts. They draw an analogy with past major extinction events, like the so-called ‘end permian extinction’ or simply ‘the great dying’ 250m years ago, associated with the loss of 90% of Earth’s species. They claim the event was driven by a similar runaway warming event to what is occurring today.
But there’s no evidence of a massive release of permafrost methane today, let alone runaway warming. Furthermore, the paleoclimate evidence doesn’t support this interpretation of ‘the great dying’. Instead, we now know that the extinction event was tied to the injection of an extensive amount of carbon dioxide into the atmosphere via gigantic volcanic eruptions, causing warming and ocean acidification.
In contrast to this natural ancient release of carbon, we have the ability to limit the increase in carbon dioxide today by curtailing the burning of fossil fuels.
3. The models are accurate
Some claim that climate models are vastly underestimating the rate of warming and underpredicting future changes. But once again, the paleoclimate data doesn’t support that assertion.
Climate scientists measure the warming effect of greenhouse gases such as carbon dioxide by what is known as ‘climate sensitivity’. It is a measure of the warming that results from a doubling of the concentration of carbon dioxide in the atmosphere (something we could see later this century in the absence of policy action). We can estimate climate sensitivity from past periods of time where carbon dioxide levels were similar to today such as the mid-Pliocene 3m years ago, or the depths of the last ice age 20,000 years ago.
Analysis of these past climate periods reveals climate sensitivity consistent with state-of-the-art climate models. The climate models seem to be getting it right. The truth, as I like to say, is bad enough. We don’t need to exaggerate the science to motivate urgent action.
4. We are making progress
Another source of climate doomism is the notion that we’re making no progress at all when it comes to the essential task of decarbonising our societal infrastructure. It’s simply not true.
Prior to the Paris agreement in 2016, the world was looking at the better part of 4C future warming given business-as-usual emissions. Now, thanks to the progress that is being made in moving away from fossil fuels to renewable energy, global temperatures are likely to stabilise below 3C. In fact, if the nations of the world make good on their commitments at the most recent global climate conferences, warming will likely be held below 2C.
While that is still too much warming (there is widespread agreement that even above 1.5C subjects us to considerable additional risk) and promises made are easier than promises kept, every fraction of a degree matters. In short, we are making progress, though it still isn’t yet enough progress.
5. There is urgency. But there is agency too
The most famous extinction event in all of Earth history happened 66m years ago when a massive asteroid struck Earth, killing off the dinosaurs (at least, the non-avian ones; birds are technically surviving dinosaurs).
Unlike the dinosaurs, which had no ability to see what was coming, let alone act on it, we have no such excuse. We see the metaphorical asteroid that is the climate crisis coming. It is a crisis of our own making and a crisis of our own potential thwarting.
Vested interests – the fossil fuel industry in particular – have engaged in a massive disinformation campaign to confuse the public and policymakers. So we must win this battle over hearts and minds, and use our voices and our votes to ensure that politicians act on behalf of the people rather than the polluters. We can still keep warming below the 1.5C danger level. The obstacles aren’t physical or technological. They are entirely political. And political obstacles can be overcome if we all make a commitment to act. We can still preserve our fragile moment.
Michael E. Mann is presidential distinguished professor and director of the Center for Science, Sustainability and the Media at The University of Pennsylvania, US. He is author of the new book Our Fragile Moment: How Lessons from Earth’s Past Can Help Us Survive the Climate Crisis.
Main image: Kresopix/iStock
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