By Paul Rosenberg, Senior Editor

Less than a month after Hurricane Sandy ravaged the Northeast, by some measures the worst storm to hit the region since the early 19th century, the World Bank issued a new report on the kind of world that Sandy may be a harbinger of.

Turn Down The Heat: Why a 4°C Warmer World Must be Avoided warns that the world is headed toward a rise of 4 degrees Celsius (7.2 Fahrenheit ) by the end of the century and that current pledges to reduce emissions will only marginally reduce that figure.

“All regions of the world would suffer – some more than others … but the report finds that the poor will suffer the most,” the report’s press release warns.

“We need to hold warming below 2 degrees,” said World Bank Group President Jim Yong Kim. “Lack of action on climate change threatens to make the world our children inherit a completely different world than we are living in today.”

Among the key findings:

• Extreme heatwaves that without global warming would be expected to occur once in several hundred years, will be experienced during almost all summer months in many regions.

• Increases of 6 C or more in average monthly summer temperatures would be expected in the Mediterranean, North Africa, Middle East and parts of the United States.

• Sea level rise by 0.5 to 1 meter by 2100 is likely, with higher levels also possible.

• The most vulnerable regions are in the tropics, sub-tropics and towards the poles, where multiple impacts are likely to come together.

• Agriculture, water resources, human health, biodiversity and ecosystem services are likely to be severely impacted.

Unfortunately, reports such as this have become all too common with the past decade, while the gap between need and action at the highest levels has only widened. Which is why another report from a completely different angle may ultimately prove more significant.

Severe weather in North America: Perils · Risks · Insurance is a report on what has already happened in North America with the past 30-plus years. The report is from Munich Re, a global giant in the reinsurance industry, which has already paid out billions in excess costs because of global warming. Seven years ago, in the aftermath of Hurricane Katrina, Random Lengths News interviewed a climate scientist from another major reinsurance company about the connections between global warming, extreme weather and rising levels of loss. So Severe Weather was just the sort of thing we were looking for to bring our readers up to date.

The 277-page report notes that, “The number of natural catastrophes per year has been rising dramatically on all continents since 1980, but the trend is steepest for North America.”

In North America costs total more than $1 trillion for this period, with 30,000 lives lost, mostly due to heatwaves.

The report adds, “This increase is entirely attributable to weather events, as there has been a negative trend for geophysical events.”

The number of loss events has nearly quintupled since 1980, compared to a world-wide average increase of 2.5 times.

Two key factors were responsible for North America’s higher rate of increased risk, said Professor Peter Höppe, head of Geo Risk Research at Munich Re.

“It’s the connection with the humid air from the Gulf of Mexico, which increases the potential for extreme events, and then it’s the missing obstacle [an East-West mountain range] so that these air masses—these arctic air masses and sub-tropical air masses—can clash in a plain,” Höppe said.

North America has every type of weather-related peril seen on the planet. The report contains separate sections devoted to winter storms, tropical cyclones, thunderstorms, inland floods, heatwaves and droughts, and wildfires as well as sections on landslides and subsidence and heave, which frequently involve weather-related causes.

“For each peril … the individual sections explain physics and characteristics, provide maps outlining threatened regions, look at outstanding historical events, present statistical analyses, and suggest risk-reducing prevention measures,” the report explains.

The detailed analysis is supported by Munich Re’s database of comprehensive losses from natural catastrophes with more than 30,000 records to draw on—4,000 from North America alone, 3,800 of them weather-related.

Tropical cyclones are far and away the most costly and most memorable form of extreme weather covered. With overall losses of $125 billion ($62.2 billion insured), Hurricane Katrina was the costliest single event, as well as the deadliest storm, claiming 1,322 lives. On an annual basis, tropical cyclone losses averaged $15.3 billion for the 10-year period 2002 to 2011. But Höppe is reluctant to jump quickly to connect Hurricane Sandy to global warming.

“Actually, the drought this year in the U.S. … is (really) a foretaste of global warming, rather than Sandy,” he said. “We don’t derive our knowledge, our information, or our belief that global warming is already changing weather extreme patterns from single events like Sandy, but from the statistics we have,” he explained.

That’s not to say there aren’t obvious connections, though.

“At the time, when Sandy made landfall, we had far above average sea surface temperatures there along the East Coast, which made it possible that Sandy kept its strength until it made landfall.”

But there’s a lot more data about more common events, such as thunderstorms, tornados and heatwaves.

“There are other weather-related perils where we see much clearer signals, which are most of all the so-called ‘convective events’, which are all the events developing out of the thunderstorms, like tornadoes, like intense precipitation events, like straight-line winds, and also hail storms,” Höppe elaborated. “There we already have detected and actually have submitted a scientific paper on these findings. This is in the review process right now … We have detected that within the last four decades we see a significant trend toward more days with conditions in the atmosphere, which allow the development of these large thunderstorm cells.”

A warmer, moister atmosphere is a direct result of global warming, which in turn produces more of these cells.

In addition to convective storms increasing, “The other ones are certainly heatwaves—which are a direct effect of global warming … And with heatwaves there is a connection to droughts.”

This is why he feels much more confident pointing to the ongoing drought as a sign of things to come. Wildfires are also clearly increasing, although human agency in starting them is a muddling factor.

As Californians, it’s impossible to ignore the most extreme weather event in the report, a projected recurrence of something like the 3-week rainstorm that flooded California in the winter of 1861–62, turning much of the Central Valley into an enormous lake.

Similarly, smaller storms hit the state in 1969, 1986, and 1997 as well.

The report explains it’s “the result of a meteorological phenomenon known as an atmospheric river bringing a stream of warm, moist air from the Pacific into California from the southwest within a period of several weeks.”

The U.S. Geological Survey did a 2011 study of what a 1,000-year atmospheric river storm—or ARkStorm—would do. The losses would be staggering—total property losses around $400 billion (more than three Katrinas) with another $325 billion in losses due to business interruption, which will be felt for a period of five years.

“There is no connection yet” between global warming and such a storm, Höppe says, but it’s not hard to see what it would look like. “If the Pacific Ocean warms up further, then the humidity will even be more, which could be transported to California, which could result in an intense precipitation event.”

It hasn’t happened here since 1862. But Sandy’s storm surge topped Manhattan’s record set back in 1821. We have been warned. Repeatedly. But are we paying attention?