文章 Articles

A perspective on doubts

Chinese voices challenging the IPCC’s conclusions should not be taken too seriously, says Jia Hepeng, who argues that the evidence for man-made climate change is watertight.

Article image

Extensive media interest in the Intergovernmental Panel on Climate Change (IPCC) has projected the voices of Chinese scholars who question the body’s conclusions beyond the academic sphere. Their doubts, combined with the extensive cold spell this spring, have shaken many people’s confidence in the existence of man-made global warming.

In essence, these scholars believe that the consensus on the cause of global warming neglects natural factors. They say that, viewed in the context of Earth’s extensive lifespan, global warming may be a natural shift. And they insist that the evidence that climate change is man-made is not comprehensive, and thus not persuasive.

It is true that, even today, there is a great deal of uncertainty surrounding climate science. The models that serve as the basis for speculation on future climate change need further improvement. But it is also clear that these doubts are not weighty enough to overthrow a conclusion reached by thousands of scientists.

What is more, current opposition to the IPCC’s work is not based on fresh evidence. Such doubts have surfaced many times in the past 20 years, some of them raised by institutes under the patronage of interest groups such as oil companies.

Some academics refute the climate-change pattern discerned by paleoclimatologist Michael Mann, whose “hockey stick graph” shows a slight cooling trend over the past millennium, followed by the sudden appearance of warming in the twentieth century – a pattern that can only be explained by the sudden increase of greenhouse-gas emissions.

The scholars who oppose the IPCC’s conclusions insist that increased levels of carbon dioxide are not the cause of this sudden warming. This vein of thought is not new – indeed, it appeared as early as Mann’s conclusion was adapted for publication in the IPCC’s third assessment report in 2001.

In 2006, the United States-based National Academy of Sciences (NAS) published a comprehensive and authoritative data evaluation. It concluded that, no matter whether or not there was an overall cooling trend in the last millennium, a little ice age did indeed occur between the fourteenth and nineteenth centuries and, based on observable data, the temperature of the twentieth century was almost certainly the highest of the last millennium. Such a significant phenomenon cannot be explained by variations in Earth’s orbit, solar radiation or volcanic eruption. Increasing emissions of greenhouse gases appears to be the only possible cause.

It is notable that, when NAS published its report, president George Bush was still in the White House and his administration had openly indicated doubts about the IPCC’s conclusions. In this context, it seems unlikely that the NAS report was manipulated by any interest group.

Based on data from the NAS report and other published evidence approved by the international academic community, the IPCC stated in its fourth assessment report, published in 2007, that it was more than 90% certain that greenhouse-gas emissions were causing global warming.

But what about Earth’s natural variations over millions of years? Indeed, there were times that our planet had higher temperatures and a greater concentration of greenhouse gases (though these conditions were not observed, but calculated). Yet this is not strong enough evidence to overthrow the IPCC’s conclusion. Bear in mind that the panel reported only a 90% likelihood that man-made climate change is occurring. For the most part, the data the IPCC relies on cannot account for a timescale of millions of years. Thus, the other 10% may cover the possibility of extreme conditions that appear every ten million years.

However, scientific conclusions need evidence. Explaining away the current warming trend as a natural change that occurs perhaps once an eon is unreasonable and lacks evidence. In fact, in view of currently accessible evidence, there is no credible explanation for the climate change we are now experiencing other than greenhouse-gas emissions. And extreme weather, drought, flooding and hurricanes caused by global warming are appearing in our everyday life more and more frequently.

Other opponents of this conclusion maintain that the data used in the IPCC assessments has focussed mainly on the northern hemisphere and has not sufficiently covered the developing world. And yet these people are unable to find any contradictory data from the unstudied areas. Furthermore, while the IPCC admits that it has ignored some regions, it has discussed the proper application of the current data in those areas.

Moreover, it is important to note that this data collection is in line with normal statistical practice. Most studies are based on typical and effective samples. If statistical analysis required every item in a given category to be examined, then it would be impossible to conduct any work of this nature.

Sometimes we may feel the climate is actually becoming colder rather than warmer. And this year’s relentless cold wave made many suspicious of global warming theories. But regardless of whether or not the harsh winter will modify the warming trend in the long term, one thing is certain: signs of abnormal weather patterns – including prolonged cold spells – are increasingly obvious. And so, perhaps, we should not get ourselves into too much of a tangle about whether or not the degree of warming is exactly that predicted by the IPCC, at least when we are not discussing it for the purpose of pure science.

Realising the urgency of climate change and its connection with greenhouse-gas emissions, the Chinese premier Wen Jiabao set out plans to develop a low-carbon economy in China in this year’s plenary session of the National People’s Congress. The scholars that doubt the science emphasise that, while they question the certainty of climate change, they still support energy efficiency and low-carbon development – neglecting to realise that, if climate change is not an urgent issue and has no connection with greenhouse-gas emissions, then there is no need to support low-carbon development.

While there are still some uncertainties in climate science, disastrous climate patterns are already affecting us in increasing volume. And so, low-carbon development that aims to reduce carbon emissions and fossil-fuel powered energy consumption is a path we have to choose.

Jia Hepeng is editor-in-chief of Science News Bi-Weekly, published by the Chinese Academy of Sciences, and co-founder of the Climate Change Journalists’ Club.

Homepage image by slackware

Now more than ever…

chinadialogue is at the heart of the battle for truth on climate change and its challenges at this critical time.

Our readers are valued by us and now, for the first time, we are asking for your support to help maintain the rigorous, honest reporting and analysis on climate change that you value in a 'post-truth' era.

Support chinadialogue

发表评论 Post a comment

评论通过管理员审核后翻译成中文或英文。 最大字符 1200。

Comments are translated into either Chinese or English after being moderated. Maximum characters 1200.

评论 comments

Default avatar
匿名 | Anonymous

石油公司 - 并非论据


Oil companies -- not an argument

Cannot get over the same ad hominem, non-evidence based argument being repeated here. That tells us a lot about your ability to face the science based skeptics.

Default avatar
匿名 | Anonymous



Thats enough.

Poorly written article. I don't even know where to start off. I guess I will make one comment. Where is the evidence that millions of scientists agree that global warming is man made? I'd like a list of names, or institutions and their staff numbers that all agree. Otherwise, its falsifed data to make other people agree with YOUR OPINION.

Please, please for the love of anything thats important to you, stop pushing your opinions on others.

Default avatar
匿名 | Anonymous


数以百万计的科学家?谎言!一些科学家还差不多!迈克尔.曼的曲棍球棒图 - 被揭穿了,名誉扫地!没有证据支持CAGW或是相关理论。


What a ridicuulously misleading article

Millions of scientists? lie! A few scientists is the right answer! Michael Mann hockey stick graph -- debunked, discredited! No evidence to support CAGW whatsoever.

This article is replete with lies after lies. People aren't that stupid.

Default avatar
匿名 | Anonymous


文章没有从科学的角度来分析问题,而是为了迎合当局来巩固“人为的全球变暖”观点。美国国家科学院的许多成员已经开始采取行动。 NAS领导发起推动政治议程,而非科学实践。
他还谈到质疑的一方没有新的证据。他一定是错过了去年夏天Lindzen 和Choi在地球物理学研究快报上发表的论文。数据显示,消极反馈来自于基于不可靠模型假定的积极反馈。这是在整个AGW论点的关键错误。

Richard Lindzen,麻省理工学院,一个真正的世界级的气候学家。他最近所撰的一篇文章,显示出本宣传的荒谬。

Typical whitewash

The author appeals to authority, not to science, in defending Mann-made global warming. The US National Academy of Sciences has been taken to task by many of its members. The NAS leadership promotes a political agenda rather than the scientific method.
And his remark about the "conclusion reached by millions of scientists" would be funny if it did not reveal such great ignorance on his part.
He also speaks of no fresh evidence for the skeptical side. He must have missed Lindzen and Choi's paper in Geophysical Research Letters last summer. The data shows negative feedback while the unreliable models assume positive feedback. That is the key fault in the whole AGW arguement.

This recent paper by Richard Lindzen, MIT,, an actual world-class climate scientist,,
shows the absurdity of the present progaganda.

Default avatar
匿名 | Anonymous





The climate change controversy has, unfortunately, diverted attention from the very real need to reduce the polluting habits of humans. No one wants to live on a planet whose air is laden with cancer causing ingredients and whose water is filthy. If cleaning the environment once again becomes the main focus then time and energy spent arguing about the science of climate change can be devoted to restoring the beauty and livability of our earth.


Default avatar
匿名 | Anonymous



Even the IPCC admits the consensus is a fraud


Default avatar
匿名 | Anonymous



Lost in translation

The "millions of scientists" is a mis-translation. The original in Chinese was "thousands of scientists".

Default avatar
匿名 | Anonymous



Say no to imposed fear of low-carbon

From the realizing sustainable development by saving energy and protecting environment point of view, I also support changing the actual energy structure, increasing energy efficiency and the proportion of renewable energies. It agrees with our actual and future interests, and is advocated by many people. However, I object to using the "climate change" argument in every debate, and therefore creating some sort of unnecessary end-of-the-word fear by exaggerating the seriousness of the matter. It would not be a scientific attitude, and would not be one of justice, either. This article has employed an unconvincing argument in order to prove an unpersuasive point, which is not most appealing to the readers. At last, I would like to call for more scientific common sense from the reporters. I believe that in order to raise people's conscience on environmental change, neutral and scientific reports are more effective than attempts of brainwashing or misleading!