Over the last couple weeks, scientists and environmentalists have been keeping a particularly close eye on the Hawaii-based monitoring station that tracks how much carbon dioxide is in the atmosphere, as the count tiptoed closer to a record-smashing 400 parts per million. Thursday, we finally got there: The daily mean concentration was higher than at any time in human history, NOAA reported.

Don’t worry: The earth is not about to go up in a ball of flame. The 400 ppm mark is only a milestone, 50 ppm over what legendary NASA scientist James Hansen has since 1988 called the safe zone for avoiding the worst impacts of climate change, and yet only halfway to what the IPCC predicts we’ll reach by the end of the century.

“Somehow in the last 50 ppm we melted the Arctic,” said environmentalist and founder of activist group 350.org Bill McKibben, who called today’s news a “grim but predictable milestone” and has long used the symbolic number as a rallying call for climate action. “We’ll see what happens in the next 50.”

We could find out soon enough: With the East Coast still recovering from Superstorm Sandy and the West gearing up for what promises to be a nasty fire season, University of California ecologist Max Moritz says milestones like these are “an excuse for us to take a good hard look at where we are,” especially as the carbon concentration shows no signs of reversing course.

Scientists first saw the carbon scale tip past 400 ppm last summer, but only briefly; the record reported today by NOAA is the first time a daily average has surpassed that point. For the last several years concentrations have hovered in the 390s, and we’re still not to the point where the carbon concentration will stay above the 400 ppm threshold permanently. But that’s just around the corner, said J. Marshall Shepherd, president of the American Meteorological Society.

“It’s clear that sometime next year we’ll see 400 consistently,” he said. “Avoiding the future warming will require a large and rapid reduction in greenhouse gases.”

Most scientists, environmentalists, and climate-conscious policymakers agree this will require, at a minimum, slashing the use of fossil fuels, and in the meantime, taking steps to adapt for a world with higher temperatures, higher seas, and more extreme weather. For example, according to Hansen, the world will need to completely stop burning coal by 2030 if returning to 350 ppm is to remain possible. What’s the holdup? Texas Tech climatologist Katherine Hayhoe blames “the inertia of our economic system, and the inertia of our political system.” But she, like most of her peers, believe it can — and must — be done: “We have to change how we get our energy and how we use our energy.”

Some progress is being made on that front: Thanks to energy efficiency gains, increased use of renewable power, and policies to cut emissions from cars and power plants, carbon emissions in the U.S. have fallen 13 percent in the last seven years. But they’re expected to begin climbing again soon, and worldwide, 2012 saw the most carbon emissions ever. Thursday’s milestone underscores the reality that if we’re serious about addressing climate change, there’s still a long road ahead.

“So far we have failed miserably in tackling this problem,” NOAA scientist Pieter Tans, who oversees the monitoring program, told the Times.

For McKibben, the real date to mark in the history books has yet to arrive: “I don’t think this will be the turning point. The turning point will be when we do something about it.”

This story was produced as part of the Climate Desk collaboration.

The year: 1990. The venue: Palais des Nations, Geneva. The star: Margaret Thatcher, conservative icon in the final month of her prime ministership. The topic: global warming.

Thatcher went to the Second World Climate Conference to heap praise on the then-infant Intergovernmental Panel on Climate Change, and to sound, again, the alarm over global warming. Not only that, her speech laid out a simple conservative argument for taking environmental action: “It may be cheaper or more cost-effective to take action now,” she said, “than to wait and find we have to pay much more later.” Global warming was, she argued, “real enough for us to make changes and sacrifices, so that we do not live at the expense of future generations.”

The Iron Lady’s speech makes for fascinating reading in the context of 2013′s climate acrimony, drenched as it is in party politics. In the speech, she questioned the very meaning of human progress: Booming industrial advances since the Age of Enlightenment could no longer be sustained in the context of environmental damage. We must, she argued, redress the imbalance with nature wrought by development.

“Remember our duty to nature before it is too late,” she warned. “That duty is constant. It is never completed. It lives on as we breathe.”

On climate change, Margaret Thatcher, who died on Monday at age 87, was characteristically steadfast, eloquent, and divisive. “The right always forget this part of her legacy,” Lord Deben, a member of the House of Lords and chair of the U.K.’s independent Committee on Climate Change, told Climate Desk on Monday. Lord Deben served in the Thatcher government and said she was crucial in raising the profile of climate negotiations around the world, even when it was deeply unpopular amongst her colleagues. “She was determined to take this high-profile position,” he said. “She believed it was her duty as a scientist.” (Thatcher studied science while at Oxford University.) Barring a few members, “the rest of the cabinet were not convinced,” he said.

Thatcher also played an instrumental role in bringing the topic to the U.S., said Lord Deben. “It was fair to say she got George Bush [Sr.] to go to Rio,” he said of Thatcher’s high-profile entreaties to convince the then-U.S. president to attend climate talks in 1992. “She saw it as her duty to blow the trumpet.”

The Geneva appearance wasn’t her only speech about the need for strong international action. It was something of a theme across the latter years of her leadership. A year before, she shocked the U.N. general assembly in New York by issuing a challenge: “The evidence is there. The damage is being done. What do we, the international community, do about it?” The news story in the New York Times ran with the headline: “Thatcher Urges Pact On Climate.” She called for the U.N. to ratify a treaty by … 1992.

She also had a domestic plan. Thatcher told British parliament that her government would cut carbon emissions back to 1990 levels by the year 2005. This was met by skepticism by the opposition at the time (female politicians of all eras might be familiar with one such quip from the opposition benches: “The Prime Minister may talk green — she may even dress green — but there are the same old blue policies underneath.”) Lord Deben painted a picture to Climate Desk of cabinet discord over one of Thatcher’s decisions to allow for funds to protect military operations from rising sea levels. “She didn’t convince her chancellor,” he said.

Thatcher even took denialists to task, telling a Royal Society dinner in March 1990 that the evidence is “undisputed.”

I think that most of us accept this diagnosis yet hardly had I got back when I found that there are researchers who argue — and some were quoted in our newspapers last week — that temperature changes over the last hundred years have less to do with man-made greenhouse effect than with changes in solar activity, something over which we have no control at all.

She thoroughly repudiated this, positing instead a sophisticated understanding of the greenhouse gas effect and the role of CO2 emissions.

But then in 2003, Thatcher, perhaps seeing the conservative tide turning against her climate legacy, watered down the statements she made two decades earlier, calling climate action a “marvelous excuse for supra-national socialism,” and accusing Al Gore — who gained worldwide recognition for similar calls for global cooperation — of “apocalyptic hyperbole.” She wrote in her 2003 book Statecraft that “a new dogma about climate change has swept through the left-of-center governing classes.” She praised President George W. Bush for rejecting the Kyoto Protocol, despite her earlier rallying cry for environmental diplomacy. Bob Ward of the Guardian points out that Thatcher’s latter-day revisionism is peppered with information from free market think tanks from the U.S., “such as the Cato Institute and the Heritage Foundation.”

Even so, Thatcher is invoked time and time again as someone who used her position to speak passionately about the need for action from the conservative classes. Lord Deben said American politicians should imitate Thatcher’s classic conservative approach to climate change: “You hand on something better to your children than you received yourself. And she was committed to that.”

He warned of the “pure populism” of the American brand of climate denial. “It’s a sort of hillbilly approach to the world,” he said, “[that] I’m afraid is attractive to quite a large portion of the American population.”

This story was produced by Mother Jones as part of the Climate Desk collaboration.

The $50 billion drought that bedeviled the country last summer — the worst since the Dust Bowl of the 1930′s — still has its fingers around half the country. And if predictions are to be believed, it’s only going to get worse for many in the coming months.

Weekly drought figures released Thursday by the U.S. Drought Monitor, a joint project of the National Oceanic and Atmospheric Administration, the USDA, and several other government and academic partners, show the situation has worsened slightly from last week, with nearly 52 percent of the continental U.S. now suffering from a moderate drought or worse. Below-average winter snow pack and rainfall are keeping much of the country in a holding pattern. No measurable precipitation fell on most of central and northern Illinois, southern Wisconsin, central and northern Iowa, southwestern Minnesota, and the Louisiana Bayou last week. Rain that fell in the West did nothing to alleviate the drought there; in fact, parts of western Oregon and southwestern Washington have reported their driest start to a calendar year on record. The forecast for the next two weeks? Dry and dry again.

The National Oceanic and Atmospheric Administration’s Climate Prediction Center warns that drought is likely to persist for much of the West and expand across northern California and southern Oregon. Although the numbers are more optimistic across eastern Kansas and Oklahoma, with some rain on the way, drought still has a strong grip on much of Colorado, New Mexico, Utah, Nevada, and Arizona due to low snow-water (around 75 percent of normal) heading into spring and early summer. That is just the latest in a battery of warning signs that show another brutal summer on its way: California experienced its driest January-February period on record, and average winter temperatures across the contiguous U.S. were 1.9 degrees F above the 20th century average.

These figures come on the back of the spring outlook from NOAA released two weeks ago that point to hotter, drier conditions coming up across much of the U.S., and with that, flooding.

In many parts of the country, drought in fact never loosened its grip, imperiling the winter wheat crop that sustains much of the U.S. wheat industry.

This story was produced as part of the Climate Desk collaboration.

257 Beach 140th Street, a modest four-bedroom house blocks from the beach in the Rockaways, Queens, is fairly unremarkable, but it put up a hell of a fight during Hurricane Sandy. While other houses just down the street were being ripped off their foundations, 257, which had been up for sale since before the storm, suffered only a little flooding in the basement. It’s otherwise unscathed, but even that damage was enough to knock a solid 10 percent off its list price (down to $799,000 from $890,000), enough to make first-time homebuyers Matthew and Jenny Daly take a closer look.

“There are more opportunities because of everything that’s happened in the last six months,” Matthew says.

In New York City alone, Sandy racked up $3.1 billion worth of damage to homes. Many of those properties in hard-hit areas like the Rockaways and the south shore of Staten Island are still empty, awaiting repairs, government buyouts, resident squatters, or, like in the case of 257, a new owner ready to tackle a fixer-upper. Damaged homes are now on the market for as much as 60 percent off their pre-storm value, and local realtors say there’s a ready contingent of bargain-hunters waiting to pounce — sometimes, to the detriment of sellers.

This story was produced as part of the Climate Desk collaboration.

Tech optimists’ crush of the decade is surely 3D printing. It has been heralded as disruptive, democratizing, and revolutionary for its non-discriminatory ability to make almost anything: dresses, guns, even houses. The process — also known as “additive manufacturing” — is still expensive and slow, confined to boutique objets d’art or lab-driven medical prototyping. But scaled up, and put in the hands of ordinary consumers via plummeting prices, 3D printing has the potential to slash energy and material costs. Climate Desk asks: Can 3D printing be deployed in the ongoing battle against climate change?

This story was produced as part of the Climate Desk collaboration.

“I don’t see what all those environmentalists are worried about,” sneers your great uncle Joe. “Carbon dioxide is harmless, and great for plants!”

OK. Take a deep breath. If you’re not careful, comments like this can result in dinner-table screaming matches. Luckily, we have a secret weapon: A flowchart that will help you calmly slay even the most outlandish and annoying of climate-denying arguments:

This story was produced as part of the Climate Desk collaboration.

This week marked the start of the civil trial against BP over its role in the 2010 explosion at the Deepwater Horizon oil rig that killed 11 men and caused the worst spill in U.S. history. District judge Carl Barbier warned of a lengthy trial, one that could last up to three months if a deal isn’t reached earlier, and if the first three days of the trial are anything to go by, BP is in for a battery of tough questions about its safety record and procedures. As much as $17.5 billion in damages is hinged on the legal question of whether the company was “grossly negligent” in causing the deaths and the subsequent spill. Climate Desk caught up with Dominic Rushe at partner publication, the Guardian, who has been covering the trial as it unfolds.

This story was produced as part of the Climate Desk collaboration.

For most people affected by superstorm Sandy, the damage was plain to see: devastated homes, impossible traffic, even lost lives. But for Bruce Brownawell, the storm’s biggest consequences are buried under several meters of seawater. Brownawell is a marine scientist at SUNY-Stony Brook who has spent the last several years becoming intimately acquainted with the chemical makeup of mud on the floor of various bays, harbors, and inlets in the New York City area.

When Sandy hit, several local scientists saw opportunity: For Bruce, it was a chance to return to these areas and investigate how strong storm tides shifted mud around — particularly in areas close to several low-lying sewage treatment plants that were knocked out during the storm and dumped raw sewage into the water for days. To do that, he and colleague Jessica Dutton of Adelphi University strapped on mud-proof waders and headed out to Hempstead Bay off the south shore of Long Island. Climate Desk crammed onto the boat for the inside dirt.

This story was produced as part of the Climate Desk collaboration.

By 2080, Russia might witness a vast mammalian invasion, as sub-arctic European animals flee global warming and adapt to a thawing tundra. New textbooks may need to accommodate never-before-seen communities of species as climate change pits predator against predator beyond the Russian steppe. That’s what a group of Swedish researchers predict in a new climate change study published in the journal, PloS One.

“North Western Russia will be some kind of hotspot of species richness,” said Christer Nilsson, an ecology professor, via Skype from Umeå University in Sweden. “Species will be on the move and there will be new combinations of species.”

Red and fallow deer, wild boar, the Eurasian badger, rabbits, mice, and beavers will all be on the move as new tracts of habitable land open up.

In a surprising twist, Nilsson and his team found that most species in the Barents Region, which includes the northern half of Norway, Sweden, Finland, and a big chunk of Northwestern Russia, will actually be favored by climate change. Forty-three out of the 61 animals studied will expand and shift their “ranges” — or habitats — mostly in a northeasterly direction, sometimes traveling hundreds of miles.

But no one can predict how all the animals will interact in their new, climate-changed world, and far from helping animals, climate change might force new, and deadly, interactions: “Predators might be in contact with new prey,” Nilsson said.

There might be tough times ahead for the poor little tundra vole, for example, which will need to elude more foxes, badgers, pine martens, stoats, weasels, polecats, and mink. That’s because right now, only 1 percent of the area Nilsson studied is suitable for three or more predators; by 2080, that could increase to nearly 40 percent. That means turf warfare for the mountain hare and the European hare, as both vie for similar habitats.

Two major caveats exist in the report. The findings assume that humans won’t — as we are so often wont to do — get in the way of the mass movement by fragmenting animals’ habitats. And the findings only apply to the “generalists” that can adapt to changing conditions. Those that require very specific habits — the “specialists,” such as the wolverine and the Siberian flying squirrel, are going to have a much tougher time in a warmed world.

Even so, the report found something encouraging: No extinctions predicted in the area surveyed. “We couldn’t find any evidence that any species will disappear, given the climate change predictions we’ve used,” Nilsson said. Nevertheless, vulnerability of those already threatened may increase due to the introduction of new competing or predatory species.

Naturally, a climate report that shows even a glimmer of hope can be latched onto and overblown. Fox News uses Nilsson’s study to declare the “poster animal” of the climate movement, the polar bear, totally OK: “Global Warming Helps Polar Bears.”

Polar bears are north of the area the researchers studied, and are not mentioned at all in the report.

This story was produced as part of the Climate Desk collaboration.

Australia’s top government-appointed climate commissioner says this week’s heat wave is occurring amid record-breaking weather around the world. “This has been a landmark event for me,” professor Tim Flannery told Climate Desk from his home in Melbourne. “When you start breaking records, and you do it consistently, and you see it over and over again, that is a good indication there’s a shift underway — this is not just within the normal variation of things.”

Flannery is perhaps best known in the U.S. for his 2005 book The Weather Makers: The History and Future Impact of Climate Change; down under, he was named Australian of the Year in 2007, and appointed chief climate commissioner in 2011 by the current Labor government, which tasked him with communicating climate science to the Australian public (a government-funded job that may well sound unimaginable to American readers).

Flannery says the harsh weather is a sign of things to come: “What we’ve seen is the bell curve shift to the hot end. The number of very hot days is increasing quite dramatically. But we’re also encroaching on entirely new territory.”

That new territory involves record-breaking temperatures. The number of consecutive days where the national average maximum temperature topped 102.2 degrees F (39 degrees C) was broken in the last week, almost doubling the previous record set in 1973. There are now new first- and third-place winners for highest temperatures on Australia’s books, too. The number of record high temperatures has outstripped the number of record low temperatures at a 3-to-1 ratio over the last decade, according to the Bureau of Meteorology.

Several fires are still burning in Tasmania, Australia’s lush island state, where the crisis began last week. The cost of the destruction of 200 buildings there is pegged at $52.7 million, according to The Australian newspaper. Luckily — perhaps shockingly given the extent of damage — lives were spared.

Statewide total fire bans remain in force across the weekend in Australia’s most populous state, New South Wales (NSW), where at last count more than 95 fires are still burning, with 18 out of control. NSW Rural Fire Service Deputy Commissioner Rob Rogers told the Australian Broadcasting Corporation that new fires on Saturday might be “beyond the ability for fire services to suppress.”

And don’t think there’s any rest from wild weather. Not content which just record-breaking heat, the skies are now hurling Narelle — a Category 4 severe tropical storm comparable to a strong Category 3 hurricane — at the Northwest of the vast continent. Communities living along a coastline roughly as long as the stretch from New York to North Carolina are bracing for gale-force winds and heavy rains.

“There is no doubt,” Flannery said, “that climate change is playing a significant role in this. If this was just one record-breaking event you might write it off as a statistical anomaly. But that’s not what we’re seeing. We’re seeing records falling around the world.”

Flannery told Climate Desk the Australian government has confirmed he will hold his seat for the next two years, but it might not play out that way. The conservative opposition party is likely to erode the Climate Commission if elected, something that will be decided by a deeply divided electorate towards the end of this year. The election promises to be fought over the government’s carbon tax. Opposition leader Tony Abbott famously made a “blood pledge” to repeal the tax, which will lead to a carbon trading scheme.

This story was produced by Mother Jones as part of the Climate Desk collaboration.