LONDON - A push by Britain to toughen up corporate environmental disclosures will cast a spotlight on climate change dawdlers as campaigners increasingly turn to the courts to force a speedier transition to a low-carbon economy.

Almost 2,000 climate change-related lawsuits have been launched around the world to date, the bulk in the last seven years, London's Grantham Research Institute on Climate Change and the Environment showed.

While the vast majority have been aimed at public authorities, a rising number are being lodged against companies on grounds that include allegations of breaching a duty of care to prevent climate change or misleading consumers about efforts to address global warming and shifts in weather patterns.

"Vulnerable companies will be those which are meaningful contributors to climate change, or are failing to manage the risks posed by climate change to their businesses, or those presenting a green façade to consumers which is not backed up by the facts," says Isabella Hervey-Bathurst, co-manager of the Schroder ISF Global Climate Leaders fund.

Britain on Wednesday became the first G20 country to make it mandatory for more than 1,300 companies to disclose climate-related risks and opportunities, in line with the global Taskforce on Climate-related Financial Disclosures (TCFD).

Standards and frameworks such as TCFD are designed to encourage companies to be more transparent as the world strives to limit global warming to 1.5 degrees Celsius above pre-industrial norms by mid-century.

If directors are open about how they are managing the ever-changing risks of transitioning to a more climate-friendly future, they are likely to protect themselves from adverse allegations. But those that fail to engage or seek to mislead risk becoming the target of litigation, experts say.

Thomas Tayler, a sustainable finance expert at Aviva Investors, said mandatory disclosure addresses transparency, an area which litigation has focused on to date.

"However, it is likely (to) also drive other forms of litigation, focusing on inadequate or incomplete disclosures or using the information in the disclosures made to inform litigation against perceived laggards."

FULL DISCLOSURE

U.N. climate scientists warned this week there was little time left to cap global warming in line with the goals of the 2015 Paris Agreement.

Environmental law charity ClientEarth, which is involved in around 168 active cases, says transparency through frameworks such as TCFD would help - but the quality and breadth of corporate disclosures is crucial.

"Plans need to be clearly disclosed and companies need to be accountable for them, including whether they are genuinely Paris-aligned," notes Maria Petzsch, a ClientEarth climate lawyer. "Failing to do so will leave boards and their directors open to litigation."

In March, the Securities and Exchange Commission proposed mandatory rules for U.S. companies, while in the European Union thousands of companies are captured by the bloc's new Corporate Sustainability Reporting Directive.

At a global level, minimum sustainability disclosures are being consulted on but for most countries, disclosures remain voluntary and vary widely in quality and breadth.

In an effort to simplify a complex risk analysis, experts are urging governments to standardise basics, such as climate models, as leading investors warn they are prepared to challenge directors over how they account for climate risks.

"There is a large amount of uncertainty inherent in climate risk, and therefore risk reporting," notes Iggy Bassi, founder and CEO of climate technology company Cervest.

"In the absence of that (standardisation) - and in litigious societies - we can expect to see a lot of lawyers springing into action."

CLIMATE LIABILITIES

The geographic spread of lawsuits has broadened since the earliest challenges of the 1980s, with courtrooms from Argentina to Japan and Australia now grappling with cases.

Among the biggest targets so far are energy companies, responsible for the bulk of man-made emissions through the use of coal, oil and gas, with Shell, TotalEnergies , Enea and RWE all facing litigation in recent years.

As Shell appeals a landmark Dutch court ruling that ordered it to slash emissions by 45% by 2030, it also faces an ambitious challenge to hold its directors personally liable for alleged failures in tackling climate change.

In what one lawyer called a "key moment" for climate change litigation, ClientEarth - also a Shell shareholder - last month announced plans to sue Shell's 13 directors for alleged failures to adopt a strategy that truly aligns with the Paris Agreement.

Shell has said the challenges of energy supply cannot be solved by litigation and points to the need for effective, government-led policies.

"Gone are the days where shareholders will skim over the ESG part of company reporting," says Elaina Bailes, a committee member of the London Solicitor Litigation Association.

"It (ESG) is now as crucial as financial performance, and ClientEarth's argument that Shell's board has failed to promote the success of the company for its shareholders reflects this trend."

(Editing by Kirsten Donovan)