Lord Stern's report on climate change was published in 2006

Economist Lord Stern has said he is optimistic a global deal to reduce carbon dioxide emissions will be struck under Barack Obama's US presidency.

Lord Stern, who was behind the first detailed economic assessment of the impact of climate change, said US and Chinese agreement to a cut was crucial.

President George W Bush's climate views were "prehistoric" and had been seen as an obstacle, Lord Stern told the BBC.

But many now believed the new president could take a lead, he said.

Kew has a DNA bank with nearly 32,000 samples of plant DNA

Plants have never been as important to the environment, the director of Kew Gardens has said, ahead of the London conservation site's 250th anniversary.

They were vital to reduce the impact of climate change and "vast numbers of humans" needed them for medicine and food, Professor Stephen Hopper added.

Several major events will be held in 2009 to celebrate Kew's role as a world leader in plant science.

The first of these sees free public entry to the gardens on New Year's Day.

The white-clawed crayfish is a protected species

A breeding programme aimed at reversing declines of the white-clawed crayfish has produced 300 young this year in the Yorkshire Dales.

Natural England, the government's conservation body, said the success of the breeding scheme offered a ray of hope to the rare native crustacean.

The white-clawed crayfish is one of England's most threatened species.

Natural England and the Environment Agency are seeking funding to expand the programme, which began in 2003.

The white-clawed crayfish was once common in upland rivers and streams but is being driven out by its invasive cousin, the American signal crayfish.

The more aggressive American species, which was brought to the country to be farmed, also carries a "plague" which is fatal to the native crayfish.

Divers have been helping restore Indonesia's coral reefs

Scientists have reported a rapid recovery in some of the coral reefs that were damaged by the Indian Ocean tsunami four years ago.

It had been feared that some of the reefs off the coast of Indonesia could take a decade to recover.

The New York-based Wildlife Conservation Society (WCS) found evidence of rapid growth of young corals in badly-hit areas.

A spokesman said reefs damaged before the tsunami were also recovering.

Some communities were abandoning destructive fishing techniques and even transplanting corals into damaged areas, the WCS said.

The number of tigers has fallen from 3,000 to 500 in the last 50 years

Malaysia has launched a national plan to double the country's wild tiger population by 2020, activists say.

Conservation groups and the government have set an ambitious target of expanding the tiger population from 500 to around 1,000 over 12 years.

Numbers have fallen sharply in recent decades because of illegal hunting.

Conservationists say new security measures will prevent poaching and that jungle corridors will be restored so tigers can roam over larger areas.

The National Tiger Action Plan is the government's first concerted effort to reverse the decline in tiger numbers, instead of merely slowing it.

Although Malayan tigers have been protected by wildlife laws since the early 1970s, their numbers have been hit by demand for their meat and for body parts which are sometimes used in traditional Chinese medicine.

Authorities estimate the wild tiger population has fallen from 3,000 to 500 in the past 50 years, largely due to illegal hunting and the human encroachment and destruction of the tigers' natural jungle habitat.

Malaysia's tropical forests are home to a wide range of threatened animals, including orang-utans, Borneo sun bears, Sumatran rhinoceroses and pygmy elephants.

Natural England is considering siting the birds in lowland areas

Hen harriers are nearing extinction in England owing to illegal persecution in areas managed for rearing game birds, Natural England has said.

The conservation watchdog said the birds of prey were persecuted at communal winter roosts.

In a 12-month period it found six birds fitted with satellite transmitters disappeared from the north Pennines.

The Royal Society for the Protection of Birds said the birds of prey were "not pests to be killed out of hand".

A spokesman for the British Association for Shooting and Conservation (BASC) said it condemned any illegal killing of protected species.

Natural England reported that hen harriers were particularly at risk from systematic persecution and disruption in areas managed for rearing red grouse or game-birds.

Just 26% of breeding pairs on red grouse moors managed to produce fledged chicks, it was reported.

The six missing birds vanished from parts of the north Pennines managed as driven grouse moors.

Natural England chairman Sir Martin Doughty said: "The hen harrier has unfortunately become the emblem of man's callous disregard for the spectacular and majestic wildlife that we have in England.

"Following seven years of intensive monitoring and detailed research, the picture is unequivocal - hen harriers are being persecuted while they attempt to nest and birds are simply not returning to their breeding areas the following spring."

Mr Holdren says climate change is already causing widespread harm

US President-elect Barack Obama has nominated two leading global warming specialists for key science posts in his administration.

Harvard physicist John Holdren will be Mr Obama's scientific adviser while marine biologist Jane Lubchenco will head the US oceanic research body.

Both have advocated greater government action on climate change.

Their appointments have been seen as a sign of Mr Obama's commitment to tackling environmental issues.

In his weekly address, Mr Obama said that "today, more than ever before, science holds the key to our survival as a planet and our security and prosperity as a nation".

He said it was "time we once again put science at the top of our agenda" and that he was confident that the US could "lead the world into a new future of peace and prosperity".

The corncrake had been struggling to hold on in the UK

The number of corncrakes in Scotland is estimated to have fallen for the first time in a decade, it has been warned.

RSPB Scotland said the population of calling males had dropped by about 8%, from 1,236 in 2007 to 1,140 this year.

The drop comes despite a successful programme to boost numbers which has seen them steadily rising since 1998.

The migratory birds have strongholds in the Hebridean and Argyll islands, where the vast majority of the UK population can be found.

A recovery programme was launched in 1993 in an attempt to increase the corncrake population in their Scottish areas.

The fall in number this year represents only the second such drop since the start of the initiative.

Mr Chu won the Nobel Prize for physics in 1997

Barack Obama has named physics Nobel Prize winner Steven Chu as his energy secretary and tasked him with finding alternatives to fossil fuels.

The US president-elect said the new administration's priorities were to end US dependence on foreign oil and fight climate change.

Naming his environment team, he said US energy dependence had grown even as global resources were disappearing.

Mr Obama has pledged to make big changes in environmental policies.

After eight years, he said, the US could not accept more broken promises when the new administration took over on 20 January.

Despite the current economic crisis, the president-elect has vowed to make the environment a priority with an ambitious promise of creating 2.5m new jobs, says the BBC's Andy Gallacher in Washington.

Australia has been hit by the worst drought in a century

Environmental activists have staged protests in several Australian cities against a plan to combat climate change announced by Prime Minister Kevin Rudd.

Some campaigners held up white flags to signify Australia's "surrender" to climate change, while others reportedly threw shoes at a puppet of Mr Rudd.

Under the plan greenhouse gas emissions will be cut by at least 5% by 2020 and a carbon trading scheme will be set up.

But critics say it is inadequate, with some calling it a "joke".