Climate Climate & Energy

‘Volcanoes emit more CO2 than humans’–Not even close …

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: One decent-sized volcanic eruption puts more CO2 in the atmosphere than a decade of human emissions. It's ridiculous to think reducing human CO2 emissions will have any effect.

Answer: Not only is this false, it couldn't possibly be true given the CO2 record from any of the dozens of sampling stations around the globe. If it were true that individual volcanic eruptions dominated human emissions and were causing the rise in CO2 concentrations, then these CO2 records would be full of spikes -- one for each eruption. Instead, such records show a smooth and regular trend.

(image from Global Warming Art)

‘Mars and Pluto are warming too’–No they aren’t — and what if they were?

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: Global warming is happening on Mars and Pluto as well. Since there are no SUVs on Mars, CO2 can't be causing global warming.

Answer: Warming on another planet would be an interesting coincidence, but it would not necessarily be driven by the same causes.

The only relevant factor the earth and Mars share is the sun, so if the warming were real and related, that would be the logical place to look. As it happens, the sun is being watched and measured carefully back here on earth, and it is not the primary cause of current climate change.

It’s disheartening

... can be found here (hat tip to pollster.com).

Here's the important result:

American voters tend to see Global Warming as a serious problem but are divided as to whether it's caused by human activities or long-term planetary trends.

This is important because:

Heat, hotness, and hotitude

Here are the second five of my "Top 10 climate stories of 2006," in no particular order. (The first five are here.)

2005 was hot: In early 2006, it was revealed that 2005 was a statistical tie with 1998 for the hottest year of the past 400. However, 1998 was warmed by the biggest El Nino of the 20th century, while 2005 had no such help. That means something else contributed to making 2005 so warm, and that something was almost certainly human activity. With a mild El Nino going on right now, my prediction is that 2007 will eclipse 1998 and 2005 as the hottest year of the instrumental record.

Blow and Behold

World’s biggest offshore wind farm given OK in England The world’s biggest offshore wind farm has been given the go-ahead and will soon be built 12 miles off the coast of southeast England. The quaintly named London Array, being developed by a consortium that includes Shell WindEnergy, will consist of 341 turbines. A separate 100-turbine […]

‘Global warming is part of a natural cycle’–This idea is one short step above appealing to magic

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: Current warming is just part of a natural cycle.

Answer: While it is undoubtedly true that there are natural cycles and variations in global climate, those who insist that current warming is purely natural -- or even mostly natural -- have two challenges.

First, they need to identify the mechanism behind this alleged natural cycle. Absent a forcing of some sort, there will be no change in global energy balance. The balance is changing, so natural or otherwise, we need to find this mysterious cause.

Second, they need to come up with an explanation for why a 35% increase in the second most important greenhouse gas does not affect the global temperature. Theory predicts temperature will rise given an enhanced greenhouse effect, so how or why is it not happening?

‘Vineland was full of grapes’–Or was it an early advertising campaign?

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: Newfoundland was so warm in the Medieval Warm Period that when the Vikings landed they called it Vineland and brought boatloads of grapes back to Europe.

Answer: Once again: you can't draw conclusions about global climate from an anecdote about a single region, or even a few regions. You need detailed analysis of proxy climate indicators from around the world. These proxy reconstructions have shown that the Medieval Warm Period (around the time the Vikings are said to have discovered North America) was not as pronounced or as warm as today's warmth. From NOAA's paleoclimate website comes these quotes:

A look back

Here are the first five of my "Top 10 climate stories of 2006," in no particular order.

National Academy hockey stick report: I'm not sure if this helped or hurt the cause, but it did confirm what many scientists already thought: it's hard to figure out the temperature of the earth 1,000 years ago. The IPCC's 2001 report said there was a 3 in 4 chance that the 1990s were the warmest decade, and 1998 the warmest year, of the last 1,000. According to the academy report, subsequent research suggests it's really a 50-50 proposition. In the end, we just don't know whether it was hotter 1,000 years ago or not. None of that, of course, affects our conclusion that humans are warming the climate.

‘The hockey stick is broken’–Well, no … but who’s playing hockey anyway?

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: The Hockey Stick graph -- the foundation of global warming theory -- has been shown to be scientifically invalid, perhaps even a fraud.

Answer: The first order of business here is to correct the mischaracterization of this single paleoclimate study as the "foundation" of global warming theory.

What's going on today is understood via study of today's data and today's best scientific theories. Reconstructions of past temperatures are about, well, the past. Study of the past can be informative for scientists, but it is not explanatory of the present nor is it predictive of the future. The scientific foundation of global warming theory contains much more than a few tree-rings and the temperature during the Medieval Warm Period.

RealClimate has an interesting article about what it would mean for today's climate theories if the MWP had indeed been warmer than today.

Now, about that pesky bit of sporting equipment ...

Yes, the last ice age started thawing over 20,000 years ago, but that stopped a long time ago

(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: Global warming has been going on for the last 20,000 years.

Answer: It is true that 20,000 years ago the temperature was some 8 to 10° C colder than it is today. But to draw a line from that point to today and say, "look, 20K years of global warming!" is dubious and arbitrary at best.

If you have look at this graph of temperature, starting at a point when we were finishing the climb out of deep glaciation, you can clearly see that rapid warming ceased around 10,000 years ago (rapid relative to natural fluctuations, but not compared to the warming today, which is an order of magnitude faster). After a final little lift 8,000 years ago, temperature trended downward for the entire period of the Holocene. So the post-industrial revolution warming is the reversal of a many-thousand-year trend.