By Doug Struck
Globe Correspondent

The muscled electrician working out in the gym had read the morning paper. He shook his head. “I thought this climate change stuff was something that would affect my grandkids. It’s not even going to wait for my kids!”

He is right. A report from a committee of the Intergovernmental Panel on Climate Change last week said the evidence of science shows that a warming planet already is affecting our lives, our agriculture, our water supplies, our shorelines and rivers, and many other aspects of the modern world we take for granted.
The report, latest in a 24-year drumbeat of warnings from scientists, tries to rid the Scarlett O’Hara procrastination (“I’ll think about that tomorrow!”) from preparing for an altered climate. Climate change is happening now, and affecting humans. Or, as an atmospheric researcher told the Associated Press, “The polar bear is us.”

Still, it is a very human question to ask, ‘How does it affect me?’ Sure, many millions of Vietnamese, Bangladeshis, Indians and Chinese may have to flee rising waters. And farmers in dry lands, including the US Southwest, are toast. And folks depending on mountain glaciers to feed fields and drinking supplies from the Andes, Alps and Himalayas will be increasingly out of luck.

But Boston? We are in a relative sweet spot—not too dry, not too warm, not too low. What will be the effect here?

The big-picture answer, of course, is that this is a global world and a global economy. If agriculture is disrupted on a large scale anywhere, we will feel it. If millions of climate refugees begin to move to safety, we will know the consequences. If nations begin to fight over dwindling water supplies, we will be at greater risk.

But the 2,500-page report from the IPCC also has much more specific warnings for places like Boston, places hard by the sea and likely to see more storms. “It is virtually certain that sea level rise will continue beyond the 21st century,” the report states. “Storm-related impacts and associated storm surges will be worsened,” the report says. “Beaches, sand-dunes and cliffs currently eroding will continue to do so.

“Vulnerability to flooding of railroads, tunnels, ports, roads and industrial facilities at low–lying areas will be exacerbated by rising sea levels or more frequent or intense storms.”

New construction in Boston designed with sea rise in mind may not go high enough. “Sea level rise will reduce the extreme flood return periods and will lower design-critical elevations of infrastructure such as airports, tunnels, coastal protections and ship terminals,” the report said, in what sounds very much like Boston.

Freshwater in the region will get warmer, increasing algae blooms and toxins. Streams and rivers will shrink between storms and then explode with fierce rain. Water treatment plants will be overwhelmed during severe storms, sending more raw sewage into our waters. Fisheries will be impacted as sea temperatures continue to climb and the ocean becomes more acidic.

The report warns that large urban areas like Boston carry particular risks. They create “heat island effects” that send summer temperatures soaring. Many are built on dangerous terrain—“steep slopes, lowlands next to riverbanks, open shorelines”—that aggravate risks.

Cities are filled with vulnerable elderly, women and children, the IPCC report warns. Cities are dependent on complex systems that can collapse: water distribution systems can fail, sewage treatment systems can be overloaded, delicate electrical grids break, and transportation systems may be paralyzed by blockages of key roads or flooding of tunnels and freeways.

As we saw in New Orleans during Hurricane Katrina, the poor usually bear the brunt of catastrophes. “Research in Boston suggests rising energy demands in hotter summers have meant a disproportionate impact on the elderly and the poor,” the report notes. “Climate change,” it warns, “will create a new poor.”

The IPCC report is the second of three committee reports that will feed into a larger overall look, called the Fifth Assessment, to be released in October. The third committee report will be out this week. The IPCC does not do its own research; instead it makes an exhaustive survey of the scientific studies done by others. This committee report relied on work from 309 scientist authors and editors from 70 countries, reviewing studies by 436 other authors with 1,729 expert and government reviewers, according to the IPCC.

(photo: Bostonglobe.com)