As illustrated by the work of the philosopher Thomas Kuhn, our conceptual models, our paradigms, frame our interpretation of data.
Today, it is critically important that we share an “energy convergence” view of climate change.Climate change is not a sedate, steady drift towards a slightly warmer planet. Rather, what we know is that – as extra energy is rapidly building up in the Earth’s ocean and atmosphere – the energy moves around creating pockets of incredible warmth. As you can see in the animation shown in Figure 1, 2016-2021 monthly standardized NASA ocean/atmosphere temperature anomalies identify regions of extreme warmth that jump around, as natural weather and climate variations concentrate energy in different parts of the world.
So while the Earth has warmed by a little more than a degree °C of “global warming,” this warmth is not evenly distributed. Nor is it static. At any given moment, some parts of the planet will be very warm. These locations change from month to month, but the overall area of exceptional warmth is growing explosively. As shown in the barplots on top of this animation, the area of the Earth’s surface covered with exceptional warmth is growing incredibly quickly. While the exact area jumps around from month to month, typical values have grown from about 5% of the Earth’s surface in the 2000s to more than 25% in 2021. In Southern Madagascar, where one million people face extreme food insecurity, extreme temperatures have exacerbated years of sequential droughts.
In arid and semi-arid land regions, this warming dries out vegetation, amplifying the intensity and extent of droughts and fires, which currently rage across the western United States (Figure 2). Now, in early August, ~91% of the western U.S. is experiencing drought, an area containing 58 million people, with some 56% of this region experiencing extreme or exceptional dryness (here). One UCLA climate scientist, Daniel Swain, thinks this may be the worst drought on record (here). In British Columbia, Oregon, and Washington, extreme heat contributed to 65, 116, and 78 deaths due to heat-related health problems. Rapid climate change assessments conclude that climate change made these extremes 150x more likely (here, here): “Western North American extreme heat was virtually impossible without human-caused climate change.”
But warmer temperatures also increase the risk of flooding. In humid areas, warming air temperatures are expected to increase the amount of water vapor in the atmosphere by about 8% per °C. So when relative humidity is high, and we have storms, atmospheric warming can lead to more extremely heavy rainfall events. There is simply more water to fall out of the sky. While the attribution of individual events is difficult, models indicate more variable precipitation, and observations indicate increasing extremes in humid regions. In late July, the Chinese province of Henan experienced the heaviest recorded rainfall event, with more than 550 mm of precipitation arriving in Zhengzhou on July 20th. More than 71 people died, and 11 million people were impacted as Typhoon In-fa brought devastating floods. June and July 2021 brought deadly floods to Germany and Belgium.
But sea surface temperatures change slowly, offering opportunities for long-lead forecasts. For example, last June and December, understanding the dangers associated with climate change-enhanced La Niñas helped support early concerns related to the threat of back-to-back East African droughts. Unfortunately, conditions may be conducive for a third or even fourth consecutive drought that may be looming (CHC blog).
But – we do not have to passively sit back and watch disasters unfold. This is central to climate hazard science.
Facing up to climate change, recognizing and understanding what is really going on, can be very empowering and effective.
Proactively preparing for disasters saves money, lives, and livelihoods, and improved Early Warning systems are the most cost-effective means of improving climate resilience. We need to invest in disaster risk reduction. Between 2015 and 2019, the impacts and losses associated with droughts, floods, and hurricanes surged through the interaction of increasing exposure and more extreme weather and climate, resulting in hundreds of billions of dollars/euros in losses, and impacting hundreds of millions of people. In 2020, California wildfires torched more than four million acres, an area the size of Belgium, more than twice the record-breaking season in 2018. The 2020 Atlantic Hurricane season brought an unprecedented number of tropical storms (animation). Meteorologists literally ran out of letters of the alphabet. The 2020 western U.S. drought and fires resulted in $22 billion dollars in losses, cyclones, and severe storms caused $42 and $35 billion dollars in damages (NOAA).
But, with eyes wide open, adopting an “energy convergence” perspective on climate change, climate scientists are working to rapidly increase our ability to monitor and predict weather and climate extremes. Spending relatively small sums on preparing for these extremes is irrefutable economics – it costs a lot less than having to respond afterwards – and it’s moral, it’s humanitarian, and it’s what we have to do. And we need to remember that it is the poorest people who typically suffer the most, and they do not have the resources to cope. They did not cause the problem in the first place.
But, responding to climate change, reducing our emissions, is also not all that expensive. The Intergovernmental Panel on Climate Change “Impacts of Global Warming of +1.5°C” report found that “additional annual average energy-related investments for the period 2016 to 2050 … are estimated to be around US $830 billion (988 billion euro).” We are already losing almost half this amount in weather-related losses every year. Investments on this scale would be about $100 dollars (199 euro) per person, or a little less than 1% of the expected 2022 global domestic production.
Increasing prosperity, fueled by emissions, is the root cause of the climate crisis. But the crisis can become a chrysalis, as we leverage our incredible and rapidly increasing innovation and human capacity to be better and smarter, together.
 This blog draws heavily from Cambridge Press’ new book ‘Drought Flood Fire: How climate change contributes to recent catastrophes’. DFF is also available as an audiobook (audible, google play), and on Amazon. There are chapters on temperature extremes and fires in the western US and Australia, extreme precipitation and cyclones, and how climate change is making natural climate variations like El Niños and La Niñas more intense – but creating opportunities for prediction.