We determine climate change from a long term weather data(minimum 30 years)? Is there any other method to determine CC?

IMHO, this is an important question.

The IPCC glossary https://www.ipcc.ch/pdf/assessment-report/ar5/syr/AR5_SYR_FINAL_Glossary.pdf defines climate as:

"Climate

Climate in a narrow sense is usually defined as the average weather, or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period for averaging these variables is 30 years, as defined by the World Meteorological Organization. The relevant quantities are most often surface variables such as temperature, precipitation and wind. Climate in a wider sense is the state, including a statistical description, of the climate system {WGI, II, III)." [My emphasis]

In other words, 30 years is a man made feature, not a natural feature. If the climate changes, it will not wait 30 years to do it. The change that happened at the end of the Younger Dryas stadial may have taken only 3 years. [Alley, R. B. (2000) The two-mile time machine, Princeton, New Jersey, USA, Princeton University Press.]

The IPCC defines climate change as:

"Climate change

Climate change refers to a change in the state of the climate that can be identified ..." [My emphasis again].

Thus climate change is not about changes to 30 year climate average weather, but to changes to the climate state.

So I am saying the that when talking about climate change we should realise it is not the climate but the climate state which is changing.

For instance, the climate state of the Arctic ocean is dominated by the permanent sea ice there. Should that ice vanish then we would have a change in climate state (and weather.)

2 Recommendations

2nd Feb, 2018

Drlatief Ahmad

Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir

Sir we are having a change here in Kashmir valley India from last five years which is a temperate region surrounded by mountains..But when I analyse the data it shows non significant trend....But if I analyse data every 5 years instead of a bulk of data..It shows a change of 3 to 5 degrees in average temperature...Now I am confused where I conclude...Kindly suggest....

3rd Mar, 2018

Alastair Bain McDonald

Independent Researcher

Dr Ahmad,

The idea of climate being the average weather over 30 years was mainly agreeed by Western European scientists, whose climate is dominatd by mild westerlies from the Atlantic Ocean, e.g. a maratime climate. Moreover, the dominant paradigm in the Earth sciences at that time was Uniformitarianism in which changes only happen slowly. It is now being accepted that catastrophic events can happen and the paradigm of Neocatastrophism is gaining ground.

My suggestion is that you work out you own metric for defining climate in Kashmir/the Indian sub-continent, which would include monsoons and katbatic winds from the Himalaya.

Note: the 30 year time span should be changed to 22 years, since that is the leength of the solar cycle.

1 Recommendation

3rd Mar, 2018

Drlatief Ahmad

Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir

Alastair sir, thanks a lot.....Actually when I analyse the weather data of Kashmir it is not showing any trend....But people around are with the suggestion that there is climate change.......As u know there are tow school of thoughts some are saying climate change and some not...For me it's variability.....And abnormality of weather...You kindly suggest me...How I will handle the queries...Because being an agrometerorologist.....Every eye is on me.....

3rd Mar, 2018

Alastair Bain McDonald

Independent Researcher

I see what you are saying now.

Global warming is happening but it is not global! The average temperature of the world is increasing but not to the same extent everywhere. A major feature, which is recorded in the geological record, is polar amplification. The temperatures in the tropics remain constant, but the polar regions become much warmer or cooler when the global temperature rises or falls.

For instance, there is fossil evidence for crocodiles around Greenland in the past.

But polar amplification is not well understood. IMHO, it is caused by water vapour which is an important greenhouse gas. When the poles warm the ice melts allowing water to evaporate and create water vapour which acts a a greenhouse gas causing further warming and more evaporation, i.e. there is a positive feedback effect. In the tropics, this happens every day, but eventually the water vapour condenses and creates clouds which cool the surface and break the vicious spiral. Thus the tropics have a governor preventing them from becoming too hot. The same governor will act in the polar regions when they are warm enough.

In the sub tropical deserts there is no water to evaporate, so they become very hot during the day but cool at night. Their temperature will increase due to the greenhouse effect of carbon dioxide, and they are now spreading poleward. The desertification is preceded by wild fires, as the air becomes hotter and drier.

In Kashmir, I would guess that you are now hotter before the monsoon and cooler during the monsoon which will be heavier since the oceans will evaporate more. You are probably safe from an expansion northward of the Thar desert, but the CO2 will be melting the Himalyan glaciers causing increased river flow now, but summer droughts later when the glaciers have gone.

The big question for you is what will happen when the Arctic sea ice melts? The last time there was a major Arctic sea ice melt was 10,000 years ago at the end of the Younger Dryas. Temperatures in Greenland jumped by 10C in possibly only three years. The effect in England was less extreme, and I imagine even less in Kashmir. There may have been an end to the Arabian monsoon then.

Plenty to investigate and to fear.

2 Recommendations

3rd Mar, 2018

Drlatief Ahmad

Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir

Thx sir

Many new things I got to know many new things

Can you help by adding an answer?

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