It’s already bad. But when will things get so bad that it is obviously — obviously — the worst problem in the world? How long until we go over the cliff? That depends on how much we’ve heated up already, and how fast we’re getting hotter.

We have already reached dangerous levels. The heat waves throughout the northern hemisphere this summer have cost plenty, to the economy, in human suffering, ill health, even lives lost. The wildfires in California this year were much worse than they would have been without global warming. Just last year we set a new record for the total cost (adjusted for inflation) of billion-dollar climate-related disasters. They cost the U.S. over $300 billion.

As bad as it is already, extremely bad is yet to come. Some say it’ll be when total warming since pre-industrial times reaches 2°C, others say — and I agree with them, given the costs we’ve already seen — that we’ll cross that threshhold at 1.5°C. That’s the level at which the costs, both economically and in terms of human life and suffering, will threaten our ability to cope.



We’ve already warmed by 1.1°C since the year 1900. That year was probably a few tenths of a degree hotter than pre-industrial, so we’ve already gone at least that far. Just to be conservative, let’s say the total warming we’ve experienced already is 1.1°C. Another 0.4°C will bring us to extremely bad.

Since 1975, the globe has been warming at a steady rate, but how fast is that rate? We can take the five best-known estimates of global temperature and estimate their rates of increase: data from NASA, from NOAA (the National Oceanic and Atmospheric Administration), HadCRU (the Hadley Centre/Climate Research Unit in the U.K.), Cowtan & Way (independent researchers from the University of York), and the Berkeley Earth Surface Temperature project (an independent estimate organized by one-time climate skeptic Richard Muller).

Here are yearly averages from all five data sets, set to the same baseline so they’re directly comparable:

Estimating the warming rate for each, the highest rate is for the data from Cowtan & Way, a whopping 1.91 ± 0.24 °C per century. The “±” indicates a 95% confidence interval, so the real rate is almost surely between 1.67 and 2.15 °C per century. At those rates, we’ll reach extremely bad sometime between 2036 and 2042.

The lowest estimate, from the NOAA data, gives a rate of 1.73 ± 0.26 °C per century, i.e. the rate is between 1.47 and 1.99 °C per century. According to which we’ll hit extremely bad between 2038 and 2045.

However, those rates aren’t entirely due to man-made global warming. Other factors affect global temperature which are only temporary, things like volcanic explosions, variations in the output of the sun, and the el Niño southern oscillation.

We can allow for those known factors. Using one way, we get the global temperature change due to the things that aren’t temporary fluctuations, namely: global warming. Here they are:

The fastest rate is still from the data of Cowtan & Way, at 1.84 ± 0.14 °C per century. That’s somewhere between 1.70 and 1.98 °C per century, so we hit extremely bad between 2038 and 2041. The lowest rate is again from NOAA data at 1.67 ± 0.1 °C per century, somewhere in the range 1.57 and 1.77 °C per century. We hit extremely bad between 2040 and 2044.

Bottom line: at the rate we’re going, we’ll hit extremely bad, possibly intolerable, probably between 2040 and 2045. Maybe a couple years later, maybe a couple years earlier, but it’s not far away. Most of you reading this will still be around when it happens. Your kids will be. We’re headed for a cliff and it’s not far away.

That’s at the rate we’re going. So what do we do? Hit the brakes.

That means reduce greenhouse gas emissions, mainly carbon dioxide (CO 2 ). We can’t stop immediately, that would bring such economic chaos it would also be extremely bad. If we stop immediately it’s like hitting a tree; we avoid going over the cliff only to die in the crash.

But if we make a giant effort to increase renewable energy while decreasing fossil-fuel energy (oil, coal, and gas), we can do it. We have to hit the brakes hard because there’s barely enough time to stop. That’s because we were warned that we’re headed toward a cliff over 30 years ago, but instead of stepping on the brakes we put the pedal to the metal. Now it’s time to slam on the brakes.

We can’t wait. If we wait until we reach the cliff to step on the brakes, we won’t be able to stop fast enough and we go over the edge.

But we can do it. What’s the best way? Is it a carbon tax? A cap-and-trade program? Massive investment in energy efficiency? All of the above? I don’t know.

But I do know that if governments — not just individuals but governments — don’t get started now, it’ll be too late. The problem is that even governments truly working on it aren’t doing enough, and the U.S. government insists on gunning the engine when we should be slowing down as fast as we can.

That’s where individuals come in. There’s only one way we can get the government to stop our headlong rush toward hell in a handbasket called Earth. VOTE. Vote climate. Make climate change your #1 issue in the voting booth.

For Americans, it starts this November with the mid-term elections. Vote climate.

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