# The Next 20 Years of Life on Earth: Runaway Global Heating. **URL:** \ **Category:** Great Debates\ **Created:** [January 4, 2010, 9:33pm UTC](https://boards.straightdope.com/t/the-next-20-years-of-life-on-earth-runaway-global-heating/523675 "2010-01-04T21:33:33Z")\ **Posts on this page:** 1\ **Showing post:** 135
**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\ **Post date:** [January 12, 2010, 3:01am UTC](https://boards.straightdope.com/t/the-next-20-years-of-life-on-earth-runaway-global-heating/523675/135 "2010-01-12T03:01:09Z")
> [@elfkin477](#): > > But how much data does one need to observe before it becomes reasonable to consider it? I have the national weather service page for my area bookmarked because I use it to keep track of snowfall amounts, and they also give monthly summaries about things such as temperature dev. from normal. It only goes back to 1/05 but these are the averages for the years here: > 2005: +0.33 > 2006: +2.45 > 2007: +0.325 > 2008: +0.25 > 2009: -0.69 > > 2006’s numbers do look alarming, but that’s one year. The rest of the numbers haven’t moved much at all, so it’s easy to see why one might look out their window over the past five years and think “seems like normal weather to me, what’s the fuss all about?” How much longer do they need to track trends before their observations become valid? Five more years? Ten? Twenty? 2 things to consider, and they are on the video BTW: 1. The national weather service deals mostly with just 1.6% of the surface of the earth (The USA) 2. That is not Climate, but Weather. > **[NASA](https://www.nasa.gov)** > > NASA.gov brings you the latest news, images and videos from America's space agency, pioneering the future in space exploration, scientific discovery and aeronautics research. > [@](#): > > The difference between weather and climate is a measure of time. Weather is what conditions of the atmosphere are over a short period of time, and climate is how the atmosphere “behaves” over relatively long periods of time. [http://www.youtube.com/user/greenman3610#p/u/9/QwnrpwctIh4](http://www.youtube.com/user/greenman3610#p/u/9/QwnrpwctIh4) > **[Does cold weather disprove global warming?](https://skepticalscience.com/global-warming-cold-weather.htm)** > > \Since the mid 1970s, global temperatures have been warming at around 0.2 degrees Celsius per decade. However, weather imposes its own dramatic ups and downs over the long term trend. We expect to see record cold temperatures even during global... > [@](#): > > What the science says… > > Since the mid 1970s, global temperatures have been warming at around 0.2°C per decade. However, weather imposes it’s own dramatic ups and downs over the long term trend. We expect to see record cold temperatures even during global warming. Nevertheless over the last decade, daily record high temperatures occurred twice as often as record lows. This tendency towards hotter days is expected to increase as global warming continues into the 21st Century. Climate researchers look at more than 15 (researchers also mention up to 20) years of yearly data to establish trends. [http://tamino.wordpress.com/2009/12/15/how-long/#more-2124](http://tamino.wordpress.com/2009/12/15/how-long/#more-2124) > [@](#): > > Therefore we need at least 14 years of GISS data (from 1996 to the present) to draw a confident conclusion about the most recent trend. In fact, since we have additional unaccounted-for uncertainty (such as the parameter estimates for our ARMA(1,1) model), we actually need a bit more. Let’s say that less than 15 years of data allows no confident conclusion about whether the trend in GISS data is warming or cooling. > > That does not mean that there’s been no warming trend in those 15 years — or in the last 10, or 9, or 8, or 7, or 6 years, or three and a half days. It only means that the trend cannot be established with statistical signficance. Of course, it’s another common denialist theme that “there’s been no warming.” This too is a fool’s argument; any such claims are only statements about the noise, not about the trend. It’s the trend that matters, and is cause for great concern, and there’s no evidence at all that the trend has reversed, or even slowed. --- _[View the full topic](https://boards.straightdope.com/t/the-next-20-years-of-life-on-earth-runaway-global-heating/523675)._