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“Temperature blankets” are the new hot crafting craze.
Trina Messer knew the weather in Dallas-Forth Worth had been unusually warm this year, but she hadn’t anticipated needing her clay-colored yarn in February. “Today we are expecting a high in the 90s!!!,” she marveled in a Facebook update last week, adding regretfully, “I was hoping for more blues, but it is what it is.”
Messer, a retired educator of 30 years, started crocheting in 2022, the natural evolution of a knitting habit she’d picked up while bored during the pandemic. So far, she has made several scarves and hats, a big cardigan “almost like a coat,” and even a couple of throw blankets. Then, in January, she began work on her biggest project yet: a temperature blanket.
Temperature blankets aren’t always blankets — they can be scarves, shawls, and even crocheted snakes. The basic premise, though, is the same: Over the course of a year, knitters, crocheters, and embroiderers add a new row, stitch, or square to their project every day, with the color of yarn corresponding to the temperature of the location where they live. In recent years, this community has grown massive, in essence creating a de facto visual record of climate change for thousands of locations around the world. “From December 1 until today, I’ve had over 26,000 people join,” Sarah Moerdyk, the creator and moderator of Facebook’s largest temperature blanket group, told me in February. For most of its existence, beginning in 2017, the group wasn’t “super active,” hovering around a few hundred members. “In a matter of three months, it’s really blown up.”
Messer chose to break her earth-toned palette into 10-degree intervals, ranging from a white yarn that represents temperatures below 19 degrees Fahrenheit to “chili red” for days over 110. She even has a special yarn, “silver sparkle,” to log days with snowfall. Thankfully, she’d already purchased the clay-colored yarn she’d designated for temperatures between 90 and 99 degrees, even though she hadn’t expected to need it until late March or April.
According to the National Oceanic and Atmospheric Administration, the contiguous United States just concluded its warmest meteorological winter in recorded history. Across the country, temperatures were 5.4 degrees above average; in some states, like Wisconsin, it was nearly 10 degrees above what it should have been for the period between December and February. “This is not normal,” Messer told me a couple weeks ago, when her phone showed it was 91 degrees near Dallas. “Don’t think it’s like this all the time.”
Despite temperature blankets’ resemblance to climatologist Ed Hawkins’ famous warming stripes, the concept predates his 2018 graphics. Perhaps more surprisingly, it wasn’t initially conceived as a commentary on climate change. As far as I — and others — have been able to gather, Kristen Cooper, a craftsperson and beekeeper living in northern British Columbia, was the first to come up with the concept that evolved into the modern temperature blanket challenge when she described a similar scarf pattern in a 2013 blog post. “You record the day’s highest temperature by knitting one row in the color designated for each temperature,” she wrote. By the end of the year, “you will have a visual, colorful graph of the temperatures of your area.”
Cooper told me she, in turn, had been inspired by knitter and author Lea Redmond’s “sky scarf,” a project from 2008 (and later, a book) that involved knitting a row a day in a color that “best captures the essence of the sky out your window.” Redmond was slightly skeptical of the idea that she could be the temperature blanket’s progenitor. Her project tried to capture “the embodied experience of looking at this beauty of the sky every day,” she told me. Temperature projects, by contrast, rely on numbers that people retrieve from a thermometer in their kitchen — or, “I’m guessing, a lot of people just check the internet.”
Lea Redmond’s “sky scarf,” depicting the colors of her local sky, photographed while in progress. The rainbow represents not a temperature variation, but a literal rainbow Redmond spotted in the sky that day.Courtesy of Lea Redmond
Internet data doesn’t have the immediacy of events unfolding in real-time, outside your window. But representing temperature data at all requires a level of emotional remove that Redmond, personally, was a little wary of: For example, when wildfires turned day to night in California in 2020, “temperature-wise, that would not have shown up in a temperature scarf, but in a sky scarf, that stripe would have looked like shit.”
Cooper, for her part, never finished the first temperature scarf because she realized that if she missed a day, she couldn’t accurately make it up — her rural town didn’t have its own weather station — which would defeat the whole point of the project. But while she eventually moved on, swept up by life with a new baby, the knitting world took the concept and ran with it. “I hadn’t really been following along, but every now and then, a completely random post by strangers on Facebook or Instagram will pop up showing a temperature blanket,” Cooper told me. “And I’m always so amazed at how far the concept has traveled.”
Only recently have artists started using conceptual knitting and crocheting projects as explicit commentaries on climate change. In 2017, after the inauguration of President Trump, yarn shop owner Emily McNeil and data scientist Asy Connelly launched the Tempestry Project — which uses standardized colors and ranges to create historic temperature records — half as a joke and half out of real anxiety over the possibility of climate information disappearing from government websites. “We weren’t really thinking about temperature blankets,” McNeil told me. “I guess I knew that they existed, but it wasn’t really on my radar when we started it.”
The Chicago Tempestry Collection, created by participants from all over the country. Emily McNeil’s Paleo New Normal, above, shows the annual deviation from average temperature from 1CE (on the left) to 2021CE (on the right). The darker the blue, the colder than average the year and the darker the red, the warmer than average the year.Courtesy of The Tempestry Project. Photographed by the museum.
Admittedly, sifting through all that climate data can take an emotional toll during the hours or days it takes to complete a tapestry. In addition to tapestries representing individual years, which rely on historical data rather than real-time observations, the Tempestry Project also facilitates multi-year “New Normal” tapestries that are directly inspired by Hawkins’ warming stripes. “The first one that I knit had me in tears as the colder colors just fade out, and you are never going to get those again,” McNeil said. (When I asked how they deal with the feelings brought up by the project, McNeil and Connelly told me dryly, “A lot of wine.”)
Temperature blanket knitters and crocheters can similarly feel alarmed by what’s unfolding in their hands. Moerdyk told me the warm weather in the northern hemisphere has been a big topic in the Facebook group, with some people having to quick-order summer colors or make special trips to the store to accommodate the winter heat in their projects. Perversely, the weirdness becomes kind of thrilling. “It’s fun to hear people say, ‘My colors are going nuts right now,’” Moerdyk said. Especially this early in the year, “to put all of a sudden this really warm temperature color in — it’s memorable. You’ll look back and say, ‘Oh my gosh, remember that time in February we had a 70-degree day? That was crazy.’”
The result is that temperature blankets become an accessible way of discussing climate change, without any of the political baggage. Moerdyk originally started the Facebook group for her friends but has since recorded participants from 1,114 different locations, including every state and over a dozen countries. She said the community has remained surprisingly civil despite all that diversity — some of it surely ideological. But temperature blankets are “not really a controversial topic,” Moerdyk said. “No matter what you believe in, temperature changes.”
Moerdyk, based in Michigan, shows off her finished 2017 temperature blanket.Courtesy of Sarah Moerdyk
For the thousands of hobbyists who’ve taken on temperature blanket projects, the craft becomes a way to witness the immediate changes in their environment that aren’t necessarily wholly negative. “If you’re looking at temperature blankets as a climate marker, that can get heavy,” Heather Walpole, the owner of Ewe Ewe Yarns, which sells temperature blanket starter bundles, told me. “But we’re still living our lives and we have a desire to create.”
Redmond, the sky scarf creator, finds this kind of creative intentionality to be the key. “It’s not like I invented stripes having meaning,” she joked. “But I do think most stripes on most garments in most stores in the United States today are meaningless. That just seems like such a missed opportunity.” It’s not that having a throw blanket or a scarf with weather-coordinated stripes will change the world. But displaying or wearing a beautiful object inspires others to ask questions: Where did you get that? Did you make it yourself? “They’re story sparks,” Redmond said. “They’re excuses to tell your story.”
This already weirdly warm year is still in its relatively chilly opening chapters, but the savviest knitters are already hurrying to stock up on yarns for June and July. As Messer, the Texas-based knitter, told me, “If this summer is anything like last summer,” then her blanket will have “a whole lot of burnt orange and red.”
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Jesse and Rob go back to basics on the steam engine.
Just two types of machines have produced the overwhelming majority of electricity generated since 1890. This week, we look at the history of those devices, how they work — and how they have contributed to global warming.
This is our second episode of Shift Key Summer School, a series of “lecture conversations” about the basics of energy, electricity, and the power grid for listeners of all backgrounds. This week, we dive into the invention and engineering of the world’s most common types of fossil- and nuclear-fueled power plants. What’s a Rankine cycle power station, and how does it use steam to produce electricity? How did the invention of the jet engine enable the rise of natural gas-generated electricity? And why can natural gas power plants achieve much higher efficiency gains than coal plants?
Shift Key is hosted by Jesse Jenkins, a professor of energy systems engineering at Princeton University, and Robinson Meyer, Heatmap’s executive editor.
Subscribe to “Shift Key” and find this episode on Apple Podcasts, Spotify, Amazon, YouTube, or wherever you get your podcasts.
You can also add the show’s RSS feed to your podcast app to follow us directly.
Here is an excerpt from our conversation:
Robinson Meyer: It’s interesting thinking about the deployment of steam and these Rankine cycle generators in the late 19th century for us as people who care about the power grid. These are interesting techniques as they’re deploying electricity for the first time. But the use of coal to convert water into steam and the use of steam power actually comes way earlier than any of this, right? Like, it’s steam. That is actually the 19th century — the core 19th century and late 19th century, especially — energy medium. And actually, the history of the 19th century energy is switching from wood and hydropower to coal-powered steam.
And already by the time that the Pearl Street station is built in New York, the United States is crisscrossed with steam engines. Our economy already runs on steam. It’s actually the application of steam and coal — which at that point are kind of old and fundamental technologies to economic function — to power generation. They didn’t have to make any huge discoveries around steam and coal. They were already using steam and coal in factories, they just weren’t intermediating it through the electricity grid.
Jesse Jenkins: That’s right. And in all these cases, you’re just trying to convert that steam, the expansion of that steam, into motion, whether that’s the pistons of a steam engine or the pistons of a reciprocating generator attached to a dynamo in Pearl Street, or, in a lot of factories, just a bunch of belts, right? That would then move equipment throughout the facility. It’s just a lot easier to move energy around, and more precise to do that as electricity. And so over time, the devices in industrial facilities all converted over to using electricity directly, and then you could generate your energy somewhere far away.
And this is the other, second advantage of steam turbines. What made Westinghouse so successful is that they have large economies of scale, so it’s a lot cheaper to generate power from a big steam turbine than the equivalent amount of power from a lot of little steam engines. And that wasn’t … I mean, that’s true for reciprocating engines, but they kind of top out, given their complexity.
The Pearl Strait station generators were in the 100-kilowatt scale. I think there were six of them, originally, so 600 kilowatts, and they only powered a few hundred lights, which is remarkable. These lights, the original lights, were incredibly inefficient, so it took something like 1,000 watts or more per light bulb. Whereas again, now we’re down to like, 10 to 15 watts in an efficient LED bulb. But anyway, they were in that kind of hundreds of watts scale, and that kind of maxed out the scale of the reciprocating engines. Steam turbines you could increase and increase and increase into the megawatt scale, and by doing that utilities or generators were able to lower the cost of energy while expanding customer bases.
Mentioned:
Powering the Dream: The History and Promise of Green Technology, by Alexis Madrigal
This episode of Shift Key is sponsored by …
The Yale Center for Business and the Environment’s online clean energy programs equip you with tangible skills and powerful networks—and you can continue working while learning. In just five hours a week, propel your career and make a difference.
Music for Shift Key is by Adam Kromelow.
The Senate told renewables developers they’d have a year to start construction and still claim a tax break. Then came an executive order.
Renewable energy advocates breathed a sigh of relief after a last-minute change to the One Big Beautiful Bill Act stipulated that wind and solar projects would be eligible for tax credits as long as they began construction within the next 12 months.
But the new law left an opening for the Trump administration to cut that window short, and now Trump is moving to do just that. The president signed an executive order on Monday directing the Treasury Department to issue new guidance for the clean electricity tax credits “restricting the use of broad safe harbors unless a substantial portion of a subject facility has been built.”
The broad safe harbors in question have to do with the way the government defines the “beginning of construction,” which, in the realm of federal tax credits, is a term of art. Under the current Treasury guidance, developers must either complete “physical work of a significant nature” on a given project or spend at least 5% of its total cost to prove they have started construction during a given year, and are therefore protected from any subsequent tax law changes.
As my colleague Matthew Zeitlin previously reported, oftentimes something as simple as placing an order for certain pieces of equipment, like transformers or solar trackers, will check the box. Still, companies can’t just buy a bunch of equipment to qualify for the tax credits and then sit on it indefinitely. Their projects must be up and operating within four years, or else they must demonstrate “continuous progress” each year to continue to qualify.
As such, under existing rules and Trump’s new law, wind and solar developers would have 12 months to claim eligibility for the investment or production tax credit, and then at least four years to build the project and connect it to the grid. While a year is a much shorter runway than the open-ended extension to the tax credits granted by the Inflation Reduction Act, it’s a much better deal than the House’s original version of the OBBBA, which would have required projects to start construction within two months and be operating by the end of 2028 to qualify.
Or so it seemed.
The tax credits became a key bargaining chip during the final negotiations on the bill. Senator Lisa Murkowski of Alaska fought to retain the 12-month runway for wind and solar, while members of the House Freedom Caucus sought to kill it. Ultimately, the latter group agreed to vote yes after winning assurances from the president that he would “deal” with the subsidies later.
Last week, as all of this was unfolding, I started to hear rumors that the Treasury guidance regarding “beginning of construction” could be a key tool at the president’s disposal to make good on his promise. Industry groups had urged Congress to codify the existing guidance in the bill, but it was ultimately left out.
When I reached out to David Burton, a partner at Norton Rose Fulbright who specializes in energy tax credits, on Thursday, he was already contemplating Trump’s options to exploit that omission.
Burton told me that Trump’s Treasury department could redefine “beginning of construction” in a number of ways, such as by removing the 5% spending safe harbor or requiring companies to get certain permits in order to demonstrate “significant” physical work. It could also shorten the four-year grace period to bring a project to completion.
But Burton was skeptical that the Treasury Department had the staff or expertise to do the work of rewriting the guidance, let alone that Trump would make this a priority. “Does Treasury really want to spend the next couple of months dealing with this?” he said. “Or would it rather deal with implementing bonus depreciation and other taxpayer-favorable rules in the One Big Beautiful Bill instead of being stuck on this tangent, which will be quite a heavy lift and take some time?”
Just days after signing the bill into law, Trump chose the tangent, directing the Treasury to produce new guidance within 45 days. “It’s going to need every one of those days to come out with thoughtful guidance that can actually be applied by taxpayers,” Burton told me when I called him back on Monday night.
The executive order cites “energy dominance, national security, economic growth, and the fiscal health of the Nation” as reasons to end subsidies for wind and solar. The climate advocacy group Evergreen Action said it would help none of these objectives. “Trump is once again abusing his power in a blatant end-run around Congress — and even his own party,” Lena Moffit, the group’s executive director said in a statement. “He’s directing the government to sabotage the very industries that are lowering utility bills, creating jobs, and securing our energy independence.”
Industry groups were still assessing the implications of the executive order, and the ones I reached out to declined to comment for this story. “Now we’re circling the wagons back up to dig into the details,” one industry representative told me, adding that it was “shocking” that Trump would “seemingly double cross Senate leadership and Thune in particular.”
As everyone waits to see what Treasury officials come up with, developers will be racing to “start construction” as defined by the current rules, Burton said. It would be “quite unusual” if the new guidance were retroactive, he added. Although given Trump’s history, he said, “I guess anything is possible.”
“I believe the tariff on copper — we’re going to make it 50%.”
President Trump announced Tuesday during a cabinet meeting that he plans to impose a hefty tax on U.S. copper imports.
“I believe the tariff on copper — we’re going to make it 50%,” he told reporters.
Copper traders and producers have anticipated tariffs on copper since Trump announced in February that his administration would investigate the national security implications of copper imports, calling the metal an “essential material for national security, economic strength, and industrial resilience.”
Trump has already imposed tariffs for similarly strategically and economically important metals such as steel and aluminum. The process for imposing these tariffs under section 232 of the Trade Expansion Act of 1962 involves a finding by the Secretary of Commerce that the product being tariffed is essential to national security, and thus that the United States should be able to supply it on its own.
Copper has been referred to as the “metal of electrification” because of its centrality to a broad array of electrical technologies, including transmission lines, batteries, and electric motors. Electric vehicles contain around 180 pounds of copper on average. “Copper, scrap copper, and copper’s derivative products play a vital role in defense applications, infrastructure, and emerging technologies, including clean energy, electric vehicles, and advanced electronics,” the White House said in February.
Copper prices had risen around 25% this year through Monday. Prices for copper futures jumped by as much as 17% after the tariff announcement and are currently trading at around $5.50 a pound.
The tariffs, when implemented, could provide renewed impetus to expand copper mining in the United States. But tariffs can happen in a matter of months. A copper mine takes years to open — and that’s if investors decide to put the money toward the project in the first place. Congress took a swipe at the electric vehicle market in the U.S. last week, extinguishing subsidies for both consumers and manufacturers as part of the One Big Beautiful Bill Act. That will undoubtedly shrink domestic demand for EV inputs like copper, which could make investors nervous about sinking years and dollars into new or expanded copper mines.
Even if the Trump administration succeeds in its efforts to accelerate permitting for and construction of new copper mines, the copper will need to be smelted and refined before it can be used, and China dominates the copper smelting and refining industry.
The U.S. produced just over 1.1 million tons of copper in 2023, with 850,000 tons being mined from ore and the balance recycled from scrap, according to United States Geological Survey data. It imported almost 900,000 tons.
With the prospect of tariffs driving up prices for domestically mined ore, the immediate beneficiaries are those who already have mines. Shares in Freeport-McMoRan, which operates seven copper mines in Arizona and New Mexico, were up over 4.5% in afternoon trading Tuesday.