Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.


Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup


All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Home Arguments Software Resources Comments The Consensus Project Translations About Support

Bluesky Facebook LinkedIn Mastodon MeWe

Twitter YouTube RSS Posts RSS Comments Email Subscribe

Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...

New? Register here
Forgot your password?

Latest Posts


So, why is two degrees the magic number?

Posted on 24 January 2018 by Guest Author

If we can keep the earth’s temperature from warming two degrees we’ll be fine. But if that temperature goes only a tiny bit above, we’re in trouble, right?  The latest video in Katharine Hayhoe's Global Weirding series with PBS.

0 0

Printable Version  |  Link to this page


Comments 1 to 15:

  1. The two degrees issue originated back in the 1970's. Heres the complete history from Carbon Brief, in a very nice readable article.

    1 0
  2. When this is a real important issue, why do they still need to put a stupid ad in front of the video?

    1 0
  3. 1 0
  4. Recommended supplemental readings:

    Global temperature targets will be missed within decades unless carbon emissions reversed, News, University of Southampton, Jan 22, 2018

    Climate change: is the glass half full or half empty? by Feike Sybesma, World Economic Forum, Jan 24, 2018

    1 0
  5. Knowing the actions that achieve the various mean temperature rises are very complex and beyond the understanding of most the public, including myself.  The Paris Climate Accord also referenced the goal of achieving net zero carbon emissions by 2nd half of this century.  I want this measure to recieve more attention because it is much easier to understand.  The problem simply defined is the inbalance of emissions over what can be sequestered.  I want people to think of the inbalance like a financial debt.  Since the warming we are already experiencing is causing amplifying affects (reduced ice cover to reflect light out, increased dark ocean converting light to heat, melting of tundra releasing methane, et) all of the new inbalance needs to be paid back.  The only way to reduce atmospheric carbon is to emit less than can be sequestered.  I developed this concept in a blog

    When we finally stop emitting more than we sequester, we will stop adding to our debt.  However, we are not out of debt.  How soon we stop over emitting determines how high our debt will be.  The annual increase in carbon concentration is an exact measure of how much emissions is over net zero.  Understanding a simple measure of the problem gives us a much better chance of understanding a measure of the solution.  To pay back the debt we must imagine and build a NET SEQUESTRATION ECONOMY, where our total human emissions are less than what can be sequestered.  We need to lower our carbon concentration in the atmosphere (debt) until there are no significant amplifying affects.  

    0 0
  6. Three terms need more consideration: Us, Dangerous and Sustainable.

    'Us' is a term that is wide open to interpretation. It can be used/abused to refer to any sub-set of humanity or to humans as a sub-set of life on this amazing planet. And it can easily exclude future generations (They are not Us!). The assessment of acceptability of any Private Interest (and all there is is a collective of Private Interests - even in Communism) to develop a better future for humanity (or to ensure there is a future for humanity) must be that Private Interest actions will not be expected to result in any 'Net Harm' to any other aspect of life, with more conservative caution applied when there is less understood about the potential for harm. Using the term Us does not clearly focus on protecting the future of humanity, it excuses Private Interest sub-sets.

    'Dangerous' can be perceived to be significantly different for different Private Interests. The loss of potential Profitability can be seen as 'dangerous' (by a sub-set Us). And the loss of perceptions of superiority, prosperity and opportunity can also be thought of as 'dangerous' (by a sub-set Us). For climate science and the clear understanding of the need to rapidly terminate an overdeveloped popular pursuit of profit, it is better to relate things to the Harm done to life. That consideration is more difficult for Private Interest bias to argue against (Private Interest can be expected to try to excuse a desire or belief). The activities associated with burning of fossil fuels have always done 'net harm' to other life, and understanding that it was harmful was well established in the 1960s and some harms like the SO2 and soot were addressed, sort of, eventually. And those harmful activities cannot be economically sustained even if the harm done is excluded from consideration (burning up non-renewable resources has no future). In fact, to remain economically viable the understood harms have to be increasingly excused to allow the activity to continue to be profitable/popular.

    A focus on developing sustainable human activity is the Key. And sustainable activity means all humans fitting in as a sustainable part of a sustainable robust and diverse web of life on this, or any other, amazing planet (Darwin identified that things thrive and survive based on how they adapted evolved and 'Fit in'). It also means activity that does not require excuses or denial to defend it.

    Some things can be observed to Thrive unsustainably to their ultimate demise. Humanity has the ability to think about how humanity 'collectively thrives', and act collectively to ensure that Private Interest sub-sets of humanity do not Win a better present for themselves to the detriment of any Others. The development of the gift of a sustainable and constantly improving future for all of humanity needs to become the understood Objective Measure of acceptable actions.

    The Sustainable Development Goals are a solid basis for evaluating acceptable actions and identifying what needs to be corrected. And like all well developed understandings they are open to improvement if a Good Reason is presented that improves the Understanding, but they are highly unlikely to be dramatically changed.

    Lack of responsible correction/limits of behaviour, just letting pursuit of popularity and profit produce the results it produces, developed the circumstance that made limiting global average surface temperature impacts to 1.0C impossible and limiting them to 1.5C unlikely. The need to curtail the burning of fossil fuels was understood in the 1960s, at a time when a 1.0C limit was achievable, but the required actions would have been to the detriment of many very wealthy people and would have requiring a reduction of perceptions of superiority and prosperity in the 'supposedly most advanced and developed nations'. The result of the actions of the collective of all Private Interests (all there is is the collective of Private Interests) was clearly sub-set evaluations of what was 'Dangerous' to 'Us' that resulted in over-development in dangerous unsustainable directions (and the development of misleading marketing) - and that needs to be understood to be the expected result of using Popularity and Profitability as the measure of the acceptability of Private Interest actions - and it needs to be understood that increased beliefs in the freedom of everyone to believe whatever they want and act as they wish makes things worse - that belief is Dangerous to the future of humanity because unacceptable pursuers of Private Interest can abuse 'desired beliefs' to excuse understandably unacceptable actions.

    0 0
  7. good video.

    and let us remember the maunder minimum (estimated at -.4C) caused the little ice age. so if -.4C did that, how can +2C somehow be "ok"?

    0 0
  8. Could "dangerous climate change" also include record low temperatures striking the northeastern and midwestern USA this winter season along with severe weather events caused by these cold fronts colliding with warmer, moister air from other regions?

    0 0
    Moderator Response:

    [JH] Your question does not compute. To understand why, go to the SkS Climate Science Glossay and carefully read the definitions of climate and weather

  9. Winter Solstice

    The winter has not been unusually cold yet this year.   It is only cold compared to the record warm winters we have gotten used to.  It is probably warmer than the average winter 50-75 years ago.  The issue is that people have gotten used to it always being warm.  Most people only remember the last 10 or so years of weather.

    According to the NOAA record temperatures page, in the last 30 days there were only 17 all time record cold temperatures set (only 19 in the past year).  This compares to the 177 all time high record temperatures set last summer.  The number of record lows was less than you would expect based on long term averages.  The media emphasizes the cold and ignores the heat.

    There were only 100 monthly low temperatures in the last 30 days while there were 115 mothly highs.  The daily records (in the last 30 days 7400 record lows and 4000 highs) are not as hard to break and there are a few more record lows.

    Keep in mind that the news reports are about all the cold when we see that there are as many hot monthly records as cold (it is very rare for a hot all time record to be set in the middle of winter).

    Compare the current normal cold weather to the record hot temperatures set during March 2012 when at least four locations the low temperature at night broke the previous daily highest temperature record.  Monthly records from April were broken in March (April is normally much hotter than March).  

    0 0
    Moderator Response:

    [DB] WinterSolstice is the 3rd sock puppet of banned user Pluto.  No further replies to it are necessary, as all such sock puppets are now recused from further participation here.

  10. To put a lower bound on the problem, what is the expected temperature rise in 2100 IF if we were to stop all human produced greenhouse gas emissions RIGHT NOW right now? Has anyone plugged these conditions into their computer?

    0 0
    Moderator Response:

    [JH] The use of all-caps constitutes shouting and is prohibited by the SkS Comments Policy. To emphasize a word or a sentence segment, please use bold font.

  11. Richard@10,

    The understanding I am aware of is that, in addition to the rapid ending of the burning of fossil fuels, there will need to be actions taken that remove some the created excess CO2 from the atmosphere.

    Truly responsible leadership would push for that combination of actions to minimize the peak increase of global average surface temperature and rapidly bring the CO2 levels even lower than the 2.0C levels.

    0 0
  12. One Planet @11.

    I agree with you.  However, my question remains unanswered.  Can you direct me to someone who may have run such an analysis?

    0 0
  13. Richard@12

    An evaluation of the global average temperature increase due to an immediate stopping of all fossil fuel burning does not "put a lower bound on the problem".

    Fossil fuel burning is only part of the human impacts that are producing increased GHG and resulting in increased global average surface temperature. And there is a range of climate sensitivity values that could be used for the evaluation. The detailed analysis comes down to a probabilistic evaluation through the various potential future realities (similar to the Monte Carlo financial analysis that is performed by companies to evaluate the probably outcomes of major investment opportunities).

    So doing an analysis of a hypothetical stopping of fossil fuel burning does not produce "a lower bound". Such a question may be analytically interesting, but it really would not establish anything meaningful.

    What needs to be changed and corrected in the current developed ways that humans live (particularly the biggest winners, the biggest consumers, the biggest impacting people), is presented in many sources including the IPCC reports. The presentations typically discuss the carbon budget, meaning the GHG impacts, that is still available before there is a a reasonable probability that the global average surface temperature would reach 2.0C.

    The focus of any discussion about what needs to be done should include the understanding that the current challenge is bigger because the biggest winners did not begin to responsibly behave better decades ago when the understanding of the needed changes/corrections of behaviour were very well established.

    Note that understanding is not determined by regional temporary popular opinion. And the actions of many of the biggest Winners to attempt to influence public opinion in favour of their understandably 'harmful to Others, particularly to future generations' Private Interest pursuits (understandable to the biggest winners that they had a lot to lose if the general population better understood the required corrections, and that they could gain benefit by misleading portions of the general population) is a major part of the problem they should be penalized for deliberately trying to make worse.

    There are legal cases developing (particularly in the New York region that includes the Stock Exchange where Team Trump are currently trying to get their preferred legal leaders in place) in the hopes of penalizing the real trouble making Winners at the top - the ones who are very well shielded from legal consequence - their best defence being denial of awareness of what was happening 'below them' that was undeniably very beneficial 'to them' - people who may try to claim that a particular expectation was unrealistic because things had already been pushed to a higher level of trouble 'by others' - people who would abuse an analysis of a calculated value of the global average surface temperature impact already created to claim it is unfair to 'expect them to not try to legally pursue maximizing their, and their investors, personal potential for benefit ' based on a 2.0C limit of total impacts (it is generally not illegal to mislead the general population, and the limited legal requirements for truth in product and services advertising do not apply to political advertising, but it is illegal to mislead investors). Those biggest winners likely knowing they are acting harmfully can also claim 'someone else should have to do more first - to be fair'.

    Hopefully that gives you reason to no longer care about the temperature expected if fossil fuel burning was stopped today, or tomorrow, or any other day. What is important is the understanding that the harmful impacts of burning fossil fuels needs to be ended far quicker than the games of popularity and profitability would end them. And the reluctance of people in the recent past to behave more responsibly has created an even bigger challenge today, with bigger loses required to be suffered by the ones who gambled more on getting away with not changing their minds and behaviour. They can be expected to perceive such personal loses as being 'unfair to them' but that is clearly an incorrect way of thinking about this matter. They need to be helped to better understand that.

    The climate science based understanding of a 2.0C limit (with the aspiration of rapidly correcting things to undo human impacts back down to a 1.5C level for the greater benefit of the future generations), accepted by all global leaders in the Paris Agreement, and the changes/corrections needed to have a good chance of achieving it, is what needs to be focused on, for many Good Reasons.

    0 0
  14. Richard,

    I typed "how much will temperature rise if all fossil fuel usage stops" into GOOGLE and the first hit was this article from the Conversation.  It suggests that the temeprature would rise about 0.6C more before it levels out.   There are a lot of caveats. 

    As OPOF points out, land usage and agriculture also affect temperature.  I do not think the 0.6C number includes heating from decreased albeido due to meltig of ice sheets which takes a longer time frame.  This is about what I remembered from articles I have read before, although the linked article does not provide a link or a graph to support the claim. 

    Google found several more interesting articles.

    0 0
  15. There was a discussion here at SkS a couple of years ago (I think) on the effect of a sudden complete cessation of all emissions.  Andy Skuce was involved in the discussion.  If I remember correctly, for several decades the inertia of the climate system roughly cancels the temperature drop one would expect.  So the temperature remains roughly constant — with some ups and downs — until it finally starts to decline in the next century.

    0 0

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.

The Consensus Project Website


(free to republish)

© Copyright 2024 John Cook
Home | Translations | About Us | Privacy | Contact Us