THE number of climate-driven natural disasters per year has more than doubled since the 1980s. Meanwhile, the average global temperature increased less than one degree.
We know how to slow the increase. It’s a win-win. Slowing it will keep us safer and will save all of us lots of money. Step one is to understand the enemy. How can such a small increase in temperature cause so much destruction?
We burn three-hundred-million-year-old hydrocarbons (oil, gas and coal) in vehicles and power stations, combining them with oxygen from the air. The total heat released since 1980 by all such sources would have increased global air temperature by a fraction of a degree, but most of it soon went into the oceans, so the actual increase is even less. In fact it is negligible.
Unlike engines in most cars and power stations, Earth’s engine of destruction doesn’t run on the heat of combustion, it runs on solar energy. Burning those hydrocarbons creates carbon dioxide. Increased CO2 causes our atmosphere to trap extra solar heat like a greenhouse. This is how we warmed the world by nearly one degree. So the engine of destruction runs on slightly warmed sea water? In a word: exactly.
The world’s weather is a flaky heat machine. It can turn that slightly warm water into a heat wave or a blizzard; a drought or a flood.
For example, here’s how it makes one kind of destructive engine, a hurricane. The sun warms the surface of the ocean a few degrees. One extra degree can make a huge difference. This heat evaporates some extra water. Water vapour makes the air next to the surface lighter than the air above it so the moist air rises. As it leaves the surface it sucks in air from far away that’s picking up more water vapour, etc.
This updraft soon creates stupendous forces. The Earth’s rotation makes it spin. Using only low-grade heat, a hurricane has organized itself into a monster — maybe a trillion tons of air and water vapour moving faster than Amtrak’s Acela Express. It sucks up more moisture from the warm sea as it wanders. When it makes landfall it may dump ten-billion tons of rain onto a state-sized area. All that water makes its way back down to the sea, turning slopes and creeks into never-before-seen raging rivers.
El Nino is a much bigger engine of destruction. Here’s how it works. Prevailing winds are pushing a great blob of warm water across the Pacific Ocean to the west coast of the Americas. It covers several million square kilometres. The top few hundred metres are about two degrees warmer than normal. This heat organizes worldwide extreme weather.
The extra heat in this year’s blob is more than all the heat humankind has generated in the million years or so since we tamed fire. It’s like the energy of ten million one-megaton nuclear warheads.
The blob holds only some of the extra solar warming. Self-organizing weather patterns draw upon heat energy worldwide. They deliver what weather always delivers: blizzards, heat waves, hurricanes, tornados, floods and droughts, but now they deliver more of them and they are more extreme. Climate calculations told us to expect this.
So far, China, the United States and India have had the worst damage. In the last decade it cost about a trillion dollars. We can already see that climate-driven damage in the next decade will cost much more.
We all pay these bills one way or another. Slowing down the growth of Earth’s destruction engine will reduce our risks and it will cost us all a lot less money.
Colin Gillespie is a physicist and author whose most recent book is Time One: Discover How the Universe Began. He writes a weekly weblog Science Seen.
Republished from the Winnipeg Free Press print edition January 9, 2016 D10