# What are some near term effects of Global Warming?

Many of the predictions of Global Warming models are dated in the range of ~100 years or more from the present. I'm wondering if any models or data provide predictions for the more immediate future, say $10$ - $20$ years from today.

Specifically, I'd like to hear about predictions that directly influence humans, such as weather, flooding, disease, etc.

• – arkaia Jun 29 '15 at 15:35
• technically a climate prediction is a 30+ yr prediction... – farrenthorpe Jun 29 '15 at 19:58
• See the National Climate Assessment too nca2014.globalchange.gov – farrenthorpe Jun 29 '15 at 21:28
• @farrenthorpe No, not really. – milancurcic Jul 1 '15 at 16:27
• Are there any particular impacts you're interested in? I think it's more useful to focus on a human-environment interaction (air quality, agricultural yield, groundwater) and then look for the ways that climate plays a role. Asking about all the possible impacts of climate is a bit too open-ended. Why do you want to know about near-term impacts? – Jareth Holt Jul 2 '15 at 0:13

The IPCC AR5 chapter 11 covers near-term climate change. I recommend reading the executive summary (it's only 6 pages). My summary of the summary is that near-term climate change is like long-term climate change, but scaled down and with less certainty. Surface air temperatures and upper-ocean temperatures are likely to increase, with an associated increase in atmospheric water vapor. Precipitation is likely to increase where it's already high and likely to decrease where it's already low. Summer Arctic sea ice extent is likely to decrease as well. But there is something there that I want to highlight.

The end of the executive summary talks about near-term air quality, and the beginning talks about predictability. Specifically, it mentions that emissions of chemicals that produce aerosols -- atmospheric particles that interact with solar radiation -- have a wide range of uncertainty, even in the near term. Unlike CO2, aerosols can induce a significant climate response (or at least a change in radiation) over the span of weeks and months. A change in energy use or technology, like India and China adopting sulfur control policies, can thus affect climate quickly and dramatically. This is a source of a lot of the uncertainty in near-term projections; over the long-term, CO2 dominates.

• Thanks, @Jay! Now I don't have to do the job of summarizing it. – arkaia Jul 2 '15 at 0:29

"I'm wondering if any models or data provide predictions for the more immediate future, say 10 - 20 years from today."

"Specifically, I'd like to hear about predictions that directly influence humans, such as weather, flooding, disease, etc."

Basically, I take your question to be: "How are people affected by climate change today?" The expectation being that if present trends continue, the effects may intensify in the near-future (10-20 years.)

I suggest you consider how people today are affected by extreme weather, because climate change may manifest today primarily by leading to more intense and frequent extreme weather events.

This recent paper in Nature Climate Change, Attribution of climate extreme events (2015) proposes that 'snowmaggedon' in February 2010, superstorm Sandy in October 2012 and supertyphoon Haiyan in November 2013, and, in more detail, the Boulder floods of September 2013, may have been influenced by high sea surface temperatures that had a discernible human component.

In the popular article "Study sees a ‘new normal’ for how climate change is affecting weather extremes", an author summarizes some of the major conclusion of that paper.

For example, although a moderate storm "Sandy" may have occurred regardless of the effects of global warming, computer modeling suggests it is likely that global warming augmented this storm up to a level great enough to flood the New York subway.

Climate predictions are only valid statistically, over long periods - typically >30 years. For shorter periods, any effect of climate change is lost in the random (and cyclic) variations of weather.

This means that climate predictions are never of the form "in the year 2045 we will see x happening" - specific events like that are weather. What can be predicted is "The period from 2050-2080 is likely to be different to the period from 2020-2050 in the following ways...", looking at differences in statistical measures (such as averages) over long periods.

So you will never see climate science tell you what will happen in specific near-future years. However, it may be possible to predict what general characteristics are likely to be different in the next 10-20 years compared to recent history. The shorter the time period for which the prediction is given, the less certainty there will be in the effects. This doesn't quite answer your question, but hopefully helps to put other answers into context.

• Thanks! How about 30 years then? can we say something definite about how humans will fare due to climate in 2045? – nbubis Jul 1 '15 at 9:35
• No - because of the vagaries of weather, we can't make predictions for specific years. But we might be able to say that how the period 2045-2075 is likely to be different, on average, to the period 2015-2045. Perhaps somebody who is actually an expert on climate modelling could chip in, though, because at this point I'm at the extent of my knowledge! I've added a paragraph to clarify. – Semidiurnal Simon Jul 1 '15 at 9:50
• The IPCC provides "short-term" predictions: ipcc.ch/publications_and_data/ar4/wg1/en/tssts-5-1.html and ipcc.ch/pdf/assessment-report/ar5/wg1/…. They talked about the uncertainties and all that. If I get some time I might summarize their finding. – arkaia Jul 1 '15 at 14:17
• @SimonW "we can't make predictions for specific years. But we might be able to say that how the period 2045-2075 is likely to be different, on average, to the period 2015-2045." That is exactly the point and the common misconception in the public. It is meaningless to discuss impacts of climate change on weather. It is meaningful to discuss impacts of climate change on climate, and indeed, yes, we can see the change in climate (average weather over 30+ years) even on time scales of 5-10 years. I don't think your answer is wrong, but it does not address the question. – milancurcic Jul 1 '15 at 16:24
• @milancurcic I understand what you mean - thank you. I'll try to revise my answer to better reflect this, although it still isn't quite going to answer the question ;-) – Semidiurnal Simon Jul 2 '15 at 9:58