但是2013年间，主要投资者在煤炭和石油上的投资规模都有所控制，主要是他们意识到这些资产可能最后会因气候政策而陷入困境。正如我在自己的新书《国家能源》（The Energy of Nations）中所指出的那样，在“碳追踪机构”发布2013年报告时，汇丰银行（HSBC）首席油气分析师保罗•斯佩丁在彭博社（Bloomberg）伦敦总部向投资者和媒体表示，他会建议自己银行的客户不要再在勘探新能源储量上浪费资本支出，同时把这些钱作为红利发还给投资者。他指出，考虑到这个行业近年来的盈利记录，每年1260亿美元的红利与高达6750亿美元的资本支出相比实在是太不像话了。
从那时起，石油公司面临的压力就开始与日俱增，最终石油巨头荷兰皇家壳牌公司（Royal Dutch Shell）近期决定不再资助2014年北极勘探计划、转而提高红利派发水平，事情才算是得以告一段落。
Many who worry about climate change have long been puzzled by the hundreds of billions of dollars that coal, oil, and gas companies routinely spend on developing their reserves, and finding and developing new reserves. These investments seem unstoppable, despite countless warnings that carbon emissions damage the global environment and economy.
Recently, however, key investors have pulled back on investments in coal and oil -- an unfolding trend that could potentially help negotiators working to curb climate change at the long-running United Nations climate talks. Ironically enough, the investment dropoff has less to do with fear of climate change and more to do with worries over wasteful spending.
Most experts believe that limiting warming to 2 degrees Celsius above pre-industrial times will help the environment and economy avoid further harm, a measure that climate scientists say requires leaving most unburned fossil fuels underground. How much should be left buried ranges depending whom you ask, but published estimates range between 60% to 80%.
Given that carbon-fuel companies aspire to add substantially to that stock of unburnable carbon, we can think of it as a kind of market bubble. This is wasteful spending and it could be thought of as an ever-expanding mountain of supposed assets that might one day end up unusable -- stranded by policymakers who finally begin doing some of what they have said they will do for years now.
The world's 200 biggest gas and oil companies currently spend more than $600 billion a year on expanding and developing their reserves, according to estimates of Carbon Tracker, a London-based financial think tank that I chair, published in April 2013. Over the next 10 years, accordingly, spending could exceed $6 trillion. Most of that is at some level of risk of ending up wasted.
During 2013, however, key investors curbed their investments in coal and oil, recognizing the risk that assets might end up stranded by climate policy. As I describe in my new book, The Energy of Nations, HSBC's lead oil and gas analyst, Paul Spedding, told investors and media at the launch of Carbon Tracker's 2013 report in Bloomberg's London headquarters that he would be recommending that his bank's clients stop wasting their money on capital expenditure in the search for new reserves and give it back to investors as dividends. The annual $126 billion of dividends, he pointed out, compare rather unfavorably to the $675 billion in capital expenditures given the industry's recent profitability record.
Since then, pressure on oil companies has built steadily, culminating in oil giant Royal Dutch Shell's (RDSA) recent decision to stop funding its Arctic exploration in 2014, and increase its dividend payment to investors instead.
In July, Norway-based financial services company, Storebrand, said it would pull out of 19 coal and tar sands investments in light of Carbon Tracker's analysis.
About three months later, one of the five Swedish governments' state pension funds said it would withdraw from all fossil fuel investments, for fear of assets being stranded. In November, after a Carbon Tracker briefing in Oslo, a majority emerged in the Norwegian parliament favoring withdrawal of the $800 billion state pension fund -- the biggest sovereign wealth fund in the world -- from coal.
Two other factors are reducing coal investments: China is developing legislation to clean up the air in their cities by banning coal. As a result, this has put pressure on Australian coal investments, which routinely assume a growing Chinese coal market.
Meanwhile, many oil and gas companies are ploughing an increasingly unprofitable furrow as their capital costs spiral, notwithstanding high oil prices. From 2005 to 2012, capital outlays rose 90% across the oil industry while prices haven't kept up, rising only 75%. In the period 2011-2013 capital expenditures rose a further 20%, while oil prices have actually dropped slightly. And the recent set of results shows a stark picture of capital expenditure soaring yet discoveries actually declining.
If these trends continue into 2014 and beyond, climate policymakers may find it easier than they thought to deliver on their promises.
Jeremy Leggett is Chairman of Carbon Tracker, and author of The Energy of Nations: Risk Blindness and The Road To Renaissance (Routledge, 2013).