Three steps to limit global warming

At last year’s Copenhagen climate summit, major greenhouse gas-emitting countries agreed that substantial action is required to limit the increase of global average temperature to less than 2 degrees C (3.6 degrees F), a point beyond which many scientists believe climate change will present unmanageable negative consequences for society.

In a paper published in the Proceedings of the National Academy of Sciences, climate researchers at Scripps Institution of Oceanography, UCSD, describe three steps for avoiding this warming threshold.

Top of the list is stabilizing CO2 concentrations in the atmosphere.

But, carbon dioxide control alone is not enough.

Also needed are warming-neutral pollution laws that balance the removal of aerosols that have an atmospheric cooling effect together with the removal of warming agents such as soot and ozone. Finally, reductions in methane, hydrofluorocarbons and other greenhouse gases in the atmosphere must also take place.

According to the authors, aggressive simultaneous pursuit of these strategies could reduce the probability of reaching the temperature threshold to less than 10 percent before the year 2050.

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Smallest, room-temperature laser demonstrated

Researchers in UCSD’s Jacobs School of Engineering have developed a laser smaller than the wavelength of light it emits. Measuring 1 micron or less in all three dimensions — height, width and depth — the “subwavelength” device operates at room temperature and emits a beam with a wavelength of approximately 1.4 microns.

Shrinking the size of lasers to below their wavelength of emission has been a formidable technical challenge.

Until now, the only way to operate such a nanolaser was to cool it to extreme subzero temperatures. The UCSD solution was to add super-thin layers of silica (glass) and aluminum to encase the core of each device. Using the aluminum shield gives the device superior heat-sinking properties, which is important for room-temperature operation. Up to 4 billion nanolasers could be placed on a 3-inch semiconductor wafer.

The research appears in the May issue of the journal Nature Photonics.

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Role of genetic mutations in Type 1 diabetes

Scientists from The Scripps Research Institute have provided an answer to the 40-year-old mystery of how certain genetic mutations lead to Type 1 diabetes.

Type 1 diabetes occurs when the body’s immune system attacks insulin-producing cells in the pancreas. While genes predispose people to many different types of diseases, specific genetic variations are an especially strong predictor of the development of Type 1 diabetes. In the case of Type I diabetes, three genetic variations — all located in the region of the genome called HLA for “human leukocyte antigen” — are known to dramatically increase the risk of disease.

Studying mice that possess molecules analogous to HLA molecules in humans, researchers discovered mutations that changed the charge at one end of a particular peptide-binding groove. The result of this molecular change was a higher affinity for T-cell binding producing an overreaction of the immune system.

This new molecular understanding could one day lead to novel therapies for Type 1 diabetes and other autoimmune diseases.

The study appears in the Journal of Clinical Investigation. More information at


Lynne Friedmann is a science writer based in Solana Beach.