Sometimes when I’m depressed about The State of the World I cheer myself up by thinking about how radically things have changed in my own lifetime. More and more women are at the top of their professions. Cigarettes are taboo. Same-sex marriage is now legal in my state. The Sustainable Sites Initiative is poised to transform the way we design and maintain landscapes…

Less than two years ago, I was told by a client not to say too much about climate change in a publication we were developing because the issue is a political hot potato. But just last week at its annual meeting, the American Public Gardens Association unveiled a partnership with the National Oceanic and Atmospheric Administration to educate gardeners and plant enthusiasts about the possible effects of climate change on the country’s gardens, landscapes, and green spaces. Yay APGA!

And I’m happy to report that my latest book, The Climate Conscious Gardener, which was published by Brooklyn Botanic Garden last year, has won a 2011 Garden Writers Association award. Kudos to BBG for continuing to raise critical—and potentially controversial—issues in its acclaimed handbook series. And thanks, GWA, for the recognition!

Oxfam wants us to demand action on climate change until we’re blue in the face—literally. The goal of the global anti-poverty group’s new campaign is to send a strong message to world leaders who will meet this December in Copenhagen to negotiate a new climate deal. To make the point, Oxfam is sponsoring face-painting and picture-taking sessions at festivals across the UK this summer. The photos will be used to create a giant multi-media petition.

A few years ago, I was sitting next to old-time soil geek Garn Wallace at a meeting of the Great Park Design Studio in Irvine, California. I was about to sample one of the strawberries on a fruit tray in front of us, and I must have made some lame comment about the berries being fresh picked from the strawberry fields outside the studio, which seemed to stretch toward the horizon. With a kind of nerdy, deadpan, pre-Valley-Girl Southern California twang, Garn noted that there wasn’t one living creature in the soil in those fields. No Sir Ree. That soil is blasted with fumigants like methyl bromide, then covered with acres of plastic. In which thousands of unblemished strawberries were glistening in the Southern California sun, waiting to be shipped to a supermarket near you.

Methyl bromide is a nasty chemical that is being phased out under the Montreal Protocol, the international treaty designed to protect the ozone layer. But according to scientists at MIT, sulfuryl fluoride, the fumigant being used as a replacement, is just as bad, or worse. According to Ron Prinn, director of MIT’s Center for Global Change Science, it is “4,800 times more potent a heat-trapping gas than carbon dioxide,” a potential climate change disaster.

Seeing as everyone is planting a vegetable patch this year, why not throw in some strawberry plants? First-time berry growers can find step-by-step instructions here.

Three cheers for citizen scientists! Twenty years of data compiled by an avid hiker and naturalist and analyzed by researchers at the University of Arizona in Tucson show that plants in the state’s Santa Catalina Mountains are flowering at higher elevations as summer temperatures rise. 

Dave Bertelsen told Science Daily he’s been hiking the Finger Rock trail one to two times a week since 1983 and recording what plants are in flower. His 5-mile hike starts in desert scrub and climbs 4,158 feet, ending in pine forest. He’s completed 1,206 round-trip hikes and recorded data on nearly 600 plant species. The researchers found that during the 20-year study period, summer temperatures in the region increased about 1.8 degree Fahrenheit.

Bertelson hooked up with the scientists at a 2005 meeting about monitoring plant species held by the U.S. Bureau of Land Management in which one of them, UA climatologist Michael Crimmins, discussed his need for data to study the effect of climate change on ecosystems over time. According to Theresa Crimmins, research specialist for the UA’s Arid Lands Information Center and lead author of the resulting paper, the role of citizen scientists is becoming ever more important—biological changes caused by climate change are coming fast, she says, and ”more eyes on the ground” are needed to monitor them.

Scientific American marshals the evidence on how much eating meat, especially beef, contributes to global warming—a lot, more than either transportation or industry.

Pound for pound, beef contributes more than 13 times as much to global warming as chicken, and 57 times as much as potatoes.

More bad news: According to a new study published in the current issue of Science, tree deaths in old-growth forests throughout the American West have more than doubled in recent decades. During the past decade, for example, mountain pine bark beetles have killed roughly 3.5 million acres of lodgepole pine forests in northwestern Colorado, and spruce bark beetles have also killed large areas of spruce forest in northern and southwestern areas of the state.

The study’s authors ruled out a number of possible reasons for the increasing die-offs, including air pollution, long-term effects of fire suppression, and normal forest dynamics, while concluding that regional warming and related droughts were the likely causes. Scarier still is their speculation that these deaths could lead to a series of harmful “cascading effects” on wildlife, and even more carbon dioxide in the atmosphere as there are fewer trees to absorb it and as the dead trees decaying on the forest floors become a significant source of the greenhouse gas.

What the heck does all the new data on global warming mean? For some perspective, take a look at one scientist’s very readable primer on climate change. Greg Laden, a biological anthropologist, provides not only good background but also cool facts. Here’s Laden on the major greenhouse gas:

Carbon Dioxide is a deadly poison. It is about 50% heavier than air, so where it occurs in density, in mines or certain natural vents associated with volcanics, it can accumulate in low spots. There are places in the Western Rift Valley where puddles of Carbon Dioxide form overnight while the air is still. These gas puddles can occur over puddles of water. When animals (such as antelopes) put their head down to the water to drink, they take a few whiffs of the gas and die. 

So far there are seven installments. You can find links to them here.

We already have data showing that the average global temperature has increased in the past 50 years, and that spring is arriving earlier. Now a new study by researchers at UC Berkeley and Harvard shows that all the seasons are arriving two days earlier. In non-tropical areas the hottest day of the year is coming nearly two days earlier, and the difference between summer and winter land temperatures has decreased. Winter temperatures have warmed more than those in summer—1.8 degrees Celsius (3.24 degrees Fahrenheit) and 1 degree C (1.8 degrees F) , respectively. 

KQED radio has produced an interesting follow-up to the recent Plos One paper predicting that climate change will have a dire impact on redwoods and other plants that are endemic to California, America’s biodiversity hotspot — plants found nowhere else in the world. (My blog on the paper is here.) A KQED reporter interviews the authors and finds they’re even more pessimistic than they were when they wrote the paper. One sobering prediction: Most of California’s endemic plants will die if global warming continues at its present pace. At the end of the century, redwoods could still be growing in California because adult trees are so long-lived. But since no seedlings will be able to survive, these adults will be the last redwoods on earth, a forest of the “living dead.”

On the KQED website you’ll also find an interesting slide show based on the radio interview.