Author: John Timmer

Today, the US Energy Information Administration announced that California had passed a key milestone, becoming the first state to produce five percent of its annual electricity using utility-scale solar power. This number represents more than a doubling from the 2013 level, when 1.9 percent of the state’s power came from utility-scale solar, and means that California produces more electricity from this approach than all of the remaining states combined.

The growth in California was largely fueled by the opening of two 550MW capacity photovoltaic plants, along with two large solar-thermal plants. In total, the state added nearly two GigaWatts of capacity last year alone. The growth is driven in part by a renewable energy standard that will see the state generate 33 percent of its electricity from non-hydro renewables by 2020; it was at 22 percent in 2014.

Other states with renewable standards—Nevada, Arizona, New Jersey, and North Carolina—rounded out the top five. Both Nevada and Arizona obtained 2.8 percent of their electricity from solar; all other states were at one percent or less.

A technique for editing genes while they reside in intact chromosomes has been a real breakthrough. Literally. In 2013, Science magazine named it the runner-up for breakthrough-of-the-year, and its developers won the 2015 Breakthrough Prize.

The system being honored is called CRISPR/Cas9, and it evolved as a way for bacteria to destroy viruses using RNA that matched the virus’ DNA sequence. But it’s turned out to be remarkably flexible, and the technique can be retargeted to any gene simply by modifying the RNA. Researchers are still figuring out new uses for the system, which means there are papers coming out nearly every week, many of them difficult to distinguish.

That may be precisely why the significance of a paper published last week wasn’t immediately obvious. In it, the authors described a way of ensuring that if one copy of a gene was modified by CRISPR/Cas9, the second copy would be—useful, but not revolutionary. What may have been missed was that this process doesn’t stop once those two copies are modified. Instead, it happens in the next generation as well, and then the generation after that. In fact, the modified genes could spread throughout an entire species in a chain reaction, a fact that has raised ethical and safety concerns about the work.

In one of the finest understatements of this very young century, some researchers have written that “The great distances that separate us from even the most nearby stars dictate that all measurements of the exoplanet must be made through remote sensing techniques for the foreseeable future.” Considering we struggle to put the funding together to go anywhere else in this Solar System, that foreseeable future seems to be stretched out for a long time.

But, if we’re limited to remote sensing, then there’s no excuse for not taking the time to think about what we should be looking for. When looking for life on Earth, we tend to look for green, since that’s the color of chlorophyl, the molecule that provides most of the energy for life here. As these researchers point out, green plants are a relatively recent arrival on Earth, only showing up about 450 million years ago. For 3 billion years prior to that, life was microbial.

And, while some microbial organisms get their energy through photosynthesis, a lot of others harvest light using different pigments or simply produce colored chemicals as an incidental byproduct of their metabolic activities. Microbes can range from a rich red to the dark purple of some salt-loving bacteria. So, if we’re looking to directly image signs of life on other planets, then we should think more carefully about what it might look like.

Although a growing number of countries are taking steps to reduce their carbon emissions, we’re still nowhere close to where we need to be if we want to limit future temperature changes to 2 degrees Celsius. If the coming temperature changes become too disruptive, our future selves may wish that our present selves hadn’t released so much carbon.

But they will have options other than looking back with regret. It’s possible with existing technologies to pull carbon from the air or to limit the sunlight reaching Earth. These forms of geoengineering are the subject of a new report by the National Academies of Science, funded by everyone from the NOAA and NASA to the US intelligence community. The report concludes that carbon removal from the atmosphere is technically viable, but it’s currently too expensive to see widespread use. Altering the amount of sunlight reaching the Earth, however, appears fraught with risks, both practical and political.

The report’s authors make one thing clear from the very start: it would be much, much easier to simply limit our carbon emissions now. “There is no substitute for dramatic reductions in the emissions of CO2 and other greenhouse gases,” they write, “to mitigate the negative consequences of climate change, and concurrently to reduce ocean acidification.” The report’s first recommendation is that we focus on mitigation and adaption efforts, as “these approaches do not present poorly defined and poorly quantified risks and are at a greater state of technological readiness.”

Even under normal circumstances, drought is a regular occurrence in agricultural regions. Several human-driven trends, from groundwater depletion to climate change, are expected to aggravate natural water shortages. While crops can’t be expected to be very productive during times of drought, it might be possible to at least get them to better tolerate short periods of water scarcity without dying.

Efforts to that end have largely focused on traditional breeding between commercial crops and drought-tolerant relatives. But researchers are now reporting progress with an alternative approach: genetic engineering. They have taken a signaling network that plants normally use to respond to stresses such as lack of water and have rewired it so that it responds to a molecule that’s normally used to kill fungus.

The signaling network that was used normally responds to a chemical made by plants called abscisic acid. Its response triggers longterm changes by regulating the activity of genes. But it also has a short-term effect: it helps plants hold on to water. It does this by affecting what are called “guard cells,” which form part of the openings (called stomata) that plants use to regulate the flow of gases into and out of their leaves.

Since the isolation of graphene, a one-atom-thick sheet of carbon, researchers have developed a number of other two-dimensional materials. (Yes, they are really three-dimensional; it’s just one of the dimensions is only an atom thick, and therefore negligible.) Knowledge of the periodic table would suggest that elements from the same column as carbon would have similar chemical properties, and therefore be excellent candidates for forming two-dimensional sheets. So, why hasn’t more been done with silicon, the next element down the column from carbon?

People have actually made silicene, the silicon version of graphene. But they’ve only managed to make tiny patches of it on silver surfaces; under just about any other conditions, it rapidly reacts with the oxygen in air and disintegrates.

On Monday, however, researchers announced that they’d managed to create the first device—a field effect transistor—using silicene. Since interactions with silver protected the silicon sheet, the authors fabricated a large sheet on a thin silver surface. They then capped this with aluminum oxide, which also protected the silicene. At this point, they could etch off some of the aluminum, and use the remaining metal as source and drain contacts. By depositing the alumina on a silicon dioxide surface, the resulting device acted as a field effect transistor.