Emissions of CO2 driving rapid oceanic acidification

The world's oceans are becoming acidic at an "unprecedented rate", more rapidly than at any time in the past 300 million years. In their strongest statement yet on this issue, scientists say acidification could increase by 170% by 2100. They say that some 30% of ocean species are unlikely to survive in these conditions. The researchers conclude that human emissions of CO2 are clearly to blame. The study will be presented at global climate talks in Poland next week.

In 2012, over 500 of the world's leading experts on ocean acidification gathered in California. Led by the International Biosphere-Geosphere Programme, a review of the state of the science has now been published. This Summary for Policymakers states with "very high confidence" that increasing acidification is caused by human activities which are adding 24 million tonnes of CO2 to oceans every day.

Humanity’s greenhouse gas emissions have been building up in the atmosphere and warming the planet for the past 150 years, dragging us into the uncharted Anthropocene, or age of man. Almost all of the planet's tropical mountain glaciers have retreated or disappeared in recent decades, including those in the South American Andes, Asian Himalaya, and African Rwenzoris.

The resulting meltwater is finding its way into the oceans. Globally, they are rising at an average of 3.5 millimetres per year – roughly twice the rate seen during the 20th Century. Sea levels are expected to rise by around 2.3 metres (7.6 feet) for every 1C of warming in the coming decades, according to a study published by scientists at the Potsdam Institute for Climate Research last month. Most of the rise in the past decade was thanks to thermal expansion – at higher temperatures the water takes up a greater volume because its molecules move about more. Now however glacial melt has overtaken thermal expansion as the leading cause of rising sea levels.

At the poles, change is underway of a magnitude so extreme that Earth hasn’t experienced its like for over 10 million years. The Arctic is warming at least twice as fast as anywhere else on the planet. One estimate suggests future average global warming of 2-3C, for example, would mean Arctic warming of 6-8C. This is partly because of the hot southerly winds bearing soot pollutants converging on the region. These particles absorb the sun’s rays and when they land on the surface attached to snowflakes they darken it and speed up melting.

African forest elephants decline by 62% in 10 years

African forest elephants face extinction if 'drastic measures' are not taken

Forest elephant numbers have decreased by 62% across Central Africa over the last 10 years, according to a study.

The analysis confirmed fears that African forest elephants (Loxodonta cyclotis) are heading for extinction, possibly within the next decade. Conservationists said "effective, rapid, multi-level action is imperative" in order to save the elephants. They are concerned the forest elephants are being killed for their ivory. Results of the study, undertaken by researchers from the Wildlife Conservation Society (WCS), are published in the scientific journal PLoS One. Over 60 co-authors contributed to the study, which was led by Dr Fiona Maisels, a WCS conservation scientist from the School of Natural Sciences, University of Sterling. "Although we were expecting to see these results, we were horrified that the decline over the period of a mere decade was over 60%," Dr Maisels told BBC Nature.

Elusive giants

Rhino poaching in South Africa reaches record levels

Figures from the South African government indicate that poaching for rhinoceros has increased substantially in the last year.

A record 668 rhinos were killed for their horns in 2012, up almost 50% on the number for 2011. The majority of the animals were killed in the Kruger national park, the country's biggest wildlife reserve.

Experts say that growing demand for rhino horn in Asia is driving the slaughter.

Rhinos and elephants: the secret lives of Africa's giants

Rhinos and elephants have a range of remarkable behaviours and adaptations, many of which we are only just learning. Emerging through the twilight, a beast lumbers forward, sniffing, snorting, searching for something. One of the largest animals to walk the earth, it is on a surprising mission. This black rhino is embarking on a midnight journey, seeking out other rhinos in the dark to socialise and mate with, sharing some never-before-seen tender moments.

Because despite their size, we are only just beginning to notice some remarkable behaviours and adaptations of elephants and rhinos. These two groups are the largest terrestrial animals. The three species of elephant range from 5.5 tonnes for an average male African bush elephant to 2.7 tonnes for female Asian elephants.

Rhinos, of which there are five species, can exceed 3.5 tonnes. Their size makes them relatively easy to spot and an easy target for poachers, who continue to hunt both groups of large mammal in significant numbers: elephants mainly for ivory in their tusks and rhinos for their horns. They have all been extensively studied by scientists, in the field and also in wildlife parks, breeding centres and zoos. But much about them, and what they get up to, remains a mystery, with many discoveries into their behaviour and adaptations only being made recently. We are still struggling to understand just how unique are different populations of these megafauna.