A story in the Washington Post highlights the fact that scientists have been warning us about man-made climate change for a long time.



It was 30 years ago, almost to the day, that the U.S. Senate Committee on the Environment and Public Works held hearings, convened by Sen. John H. Chafee (R-RI), on the subject of “Ozone Depletion, the Greenhouse Effect, and Climate Change.” The danger was made clear. So too was the cause: the buildup of greenhouse gases (chiefly carbon dioxide) in the atmosphere — because of us. So too was the solution: slow, and eventually halt, the rise of greenhouse gases in the atmosphere.

When 1986 drew to a close, it wasn’t quite hot enough to break the record for global temperature, that was still held by 1981. But one year later, 1987 broke the record. Another year later, in 1988, it was broken again. It happened again in 1990, and 1995, 1997, 1998, 2005, 2010, 2014, and 2015. This year — 2016 — is well on its way to breaking the record yet again. If that comes to pass, it means we’ll have set a new global temperature record 11 times since those senate hearings 30 years ago. Quite apart from the month-to-month and year-to-year fluctuations, the trend in global temperature has increased by more than 0.5 °C (0.9 °F) in that time.

Earth was already hotter than before the industrial revolution (referred to as pre-industrial), by nearly 0.6 °C. The 0.5+ °C we’ve increased since then brings us to more than 1 °C above pre-industrial. That has already brought trouble, including more and worse heat waves and wildfires, coastal flooding due to sea level rise, and changes in patterns of drought and flood. If we get to 1.5 °C above pre-industrial we’re in very serious trouble — and we’re on track to get there in just a few decades. If we get to 2 °C above pre-industrial, we’re headed for disaster.

We were warned.

Rather than heed the warning as a wise nation should, certain factions of our government have actually prevented action. The senate’s Committee on the Environment and Public Works is now headed by Jim Inhofe (R-OK), who not only denies the threat, he calls it a “hoax.” Out of 15 candidates seeking the republican party’s nomination for President of the United States last summer, the only one who took the issue seriously was eliminated very early in the running. The presumptive republican nominee, Donald Trump, has flatly stated he’ll undo what little our nation has tried to do about this problem.

What have we done with our 30 years’ warning? The necessary solution is clear, and has been all along: slow, and eventually halt, the increase of greenhouse gases in our atmosphere. We know their concentration is still increasing, but at what rate? Is the rate of rise at least slowing?

Unfortunately, no. It’s speeding up.

The two most damaging man-made greenhouse gases are carbon dioxide (CO 2 ) and methane (CH 4 ). Here’s the history of CO 2 concentration since 1958, measured at the Mauna Loa atmospheric observatory in Hawaii:

The regular up-and-down wiggles are a seasonal pattern, peaking each year in May and bottoming out in September/October. We can remove the seasonal cycle, better to see what the trend is, and I’ve done so in a rather sophisticated way (but simple ways paint essentially the same picture):

When we were warned in 1986, CO 2 concentration was about 347.5 ppm (parts per million), but now it’s about 404.5 ppm. The 1986 value was already 25% higher than the pre-industrial level, today’s value is 45% higher.

It’s a bit of a surprise how well the increase matches a system where the rate of increase is rising steadily. That would imply that the concentration is a quadratic function of time, which would compare (red line) to measured concentration (black line) thus:

If correct, that means that the rate at which CO 2 is increasing has been steadily getting faster. A direct measure of the rate of increase (by a sophisticated method, but simple ways paint essentially the same picture) also suggests a steady increase in the rate at which CO 2 is rising:

In 1960 CO 2 was only going up by less than 1 ppm/year, but now it’s increasing by more than 2 ppm/year. And, alas, it shows no sign of slowing down — just going faster and faster.

What about methane? Here’s the CH 4 concentration since 1984 measured at Cape Grim in Tasmania (south of Australia):

Again we see yearly up-and-down wiggles revealing a seasonal cycle, peaking in September and bottoming out in February/March. Again removing the seasonal pattern, we get a better picture of the trend:

The increase of atmospheric methane did slow down for a while, and from about 2000 to 2007 it stopped increasing altogether. But since 2007 it has risen again, and lately it seems to be speeding up. A direct measure confirms this picture:

The conclusion is abundantly clear: that what we need to do — slow, and eventually halt, the increase of greenhouse gases — isn’t being done. The situation isn’t getting better, it’s getting worse.

As dangerous as is our own dumping greenhouse gases in the air, there’s an even greater danger. We’ve already warmed the Earth substantially, and it continues to get hotter. When it does, stores of Carbon naturally locked safely away in places like the ocean and the soil can be released, to increase greenhouse gases in the atmosphere even if we stop burning fossil fuels.

As the temperature of the ocean increases, its ability to dissolve CO 2 decreases. Enough warming of the oceans will cause them to release some of the massive CO 2 they’ve already sequestered, driving up its concentration in our air. That will make the problem of global warming worse.

Perhaps the most worrisome threat is that because the Arctic is warming so much faster than the globe as a whole, the permafrost — soil that remains frozen year-round — is thawing. As it does, organic matter which is trapped within can decay, and when it does it releases CO 2 into the atmosphere, except those places where instead of releasing CO 2 it releases CH 4 .

Those two great reservoirs, the oceans and the permafrost, have the potential to dump more CO 2 into the atmosphere than all of mankind’s burning of fossil fuels over the centuries. If they give up their carbon, the climate impact will be devastating. Worse yet, we’ll be at a loss to stop it.

So yes, I worry. We need to slow, and eventually (soon!) halt, the increase of greenhouse gases in our atmosphere. But so far, in spite of 30 years of unambiguous warning by the best scientific minds, our government here in the U.S. has done nothing but resolve to do nothing.

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