Why humans live on Earth and not Venus
Earth's first crust - rich in radioactive heat-producing elements such as uranium and potassium, was torn from the planet when asteroids bombarded it early in its history, according to research published in the Nature Geoscience journal.
Researchers at the University of British Columbia (UBC) and the University of California, Santa Barbara, say that the early loss of these two elements determined the evolution of Earth's plate tectonics, magnetic field and climate.
"The events that defined the early formation and bulk composition of Earth govern, in part, the subsequent tectonic, magnetic and climatic histories of our planet, all of which have to work together to create the Earth in which we live," said Professor Mark Jellinek of the Department of Earth, Ocean and Atmospheric Sciences at UBC.
"It's these events that potentially differentiate Earth from other planets."
Venus is the most similar planet to Earth in terms of size, mass, density, gravity and composition. But Earth has had a stable and habitable climate, while Venus has a thick carbon dioxide atmosphere and surface temperatures reaching about 470 deg C. The study explains why the two planets could have evolved so differently, said UBC.
Earth could have ended up like Venus, said Prof Jellinek. "A key difference that can tip the balance... may be differing extents of impact erosion... We were able to show that the effect of the conditions governing the initial composition of a planet can have profound consequences for its evolution.
"It's a very special set of circumstances that make Earth."
Trees take years to recover from droughts
It takes years for trees to resume normal growth after droughts end, suggesting that they are capable of storing less carbon than climate models have calculated, shows new research.
Forests reduce the impact of climate change by removing massive amounts of carbon dioxide emissions from the atmosphere and incorporating the carbon into woody tissues.
"If forests are not as good at taking up carbon dioxide, this means climate change would speed up," says lead author of the study William Anderegg, assistant professor of biology at the University of Utah.
He co-authored the study with researchers from Princeton University, Northern Arizona University and NOAA Geophysical Fluid Dynamics Laboratory, among others.
Prof Anderegg and his team tracked the recovery of tree stem growth after severe droughts since 1948 at over 1,300 forest sites worldwide using records from the International Tree Ring Data Bank. Tree rings provide a history of wood growth and track the carbon uptake of the ecosystem in which the tree grew.
While a few forests showed that observed growth was higher than predicted after drought, the majority of the world's forests and trees struggled for years. On average, trunk growth took two to four years to return to normal. Growth was about 9 per cent slower than expected in the first year of recovery, and was 5 per cent slower in the second year.
Long-lasting effects of drought were most prevalent in dry ecosystems. Prof Anderegg said: "This really matters because, in the future, droughts are expected to increase in frequency and severity due to climate change."
New NGO aims to reduce food waste in Singapore
A new non-government organisation (NGO) has been set up to encourage Singaporeans to think twice about what they throw away.
Set up by Mr Eugene Tay, 37, who runs an environmental consultancy firm Green Future Solutions, the NGO called Zero Waste Singapore aims to promote awareness on how waste can be reduced.
The group will hold talks and workshops for schools and firms, and survey residents on how they recycle household items.
Said Mr Tay: "A lot of work needs to be done to encourage our domestic recycling rate to go up."
The domestic recycling rate last year fell to 19 per cent from 22 per cent in 2010, according to the National Environment Agency (NEA), which said this was largely due to a 30 per cent rise in food waste output in the period.
The Government hopes to raise the domestic recycling rate to 30 per cent by 2030.
Mr Tay said food-waste reduction will be the focus for his NGO this year. "NEA is stepping up its efforts on reducing food waste, so it's the right time for us to focus on that and complement its efforts with increased awareness and education."
Food waste in the domestic sector is not segregated for recycling. If placed with recyclables, it would contaminate the lot, which must then be discarded.
Compiled by Carolyn Khew