DON'T BELIEVE IT!
Look at the actual evidence before falling into their trap. I will do a separate post comparing 2010 to other years, but this post will very likely show you what I expect to see. Nothing unusual about 2010.
It's all about record breaking days. They manipulate that to mean what they want you to believe. Record breaking days is not about the planet heating up. It's an accounting issue only. Since we do not have accurate records before 1900, there is no way of knowing if some specific day indeed is the "hottest on record". The fact that they include the word "record" is the key that this is accounting only.
Take this thought experiment as an example. You travel back in time to 1900, and set up a station to record accurate temperature data. Guess what? EVERY DAY IS A RECORD BREAKER! That's because you have nothing to compare it too. As the years move on, that year maintains its "record" temps until some day where it happens to land above one of those record days from 1900, and low and behold a new record temperature! Doesn't matter that the new day, say July 5 1911 is 30C, it's a record breaking day!
Eventually as time goes on, some year will break some day and be heralded as a record breaking temp. The problem is eventually, the number of record breaking days will start to drop for each year as the accounting accumulates more and more data. Eventually you get to the point where no more years will have any record breaking days. That time has yet to come, and actually can be simulated with a software program that randomly assigns a temp within a range to future days and plotting the number of record days in each year. I don't have to create such a program to know that eventually some time in the future, there will be no more record breaking days. It may be 100 years from now for there to be enough data accumulated for that to occur, but it will happen. Then what will the warmists do! AGW will very likely be a scam of the past by then.
What we can do now is see what the record breaking days in summer have been so far since 1900 using Ottawa's station (4333).
The verticle axis is the number of days since May 1 in the summer months until end of September. The X axis is the year that each record occurred. The dots represent the highest, or record breaking, temp on that day. You will see that those record breaking days cluster before 1930.
Those record breaking days have a narrow range of actual temperatures when viewed this way:
The Y axis is the record temp, the X axis is the number of days since May 1, and each dot is the year the record was set. There is a clear band of temps. It would appear that there is an upper limit to how "hot" any given day can actually get for this location. For example, it would be physically impossible for the first day of May to get to 38C. likely not possible to get above 32C. This would be true for any location which would have their own upper limit to how hot any day can get. Record breaking days are attempts to get to that ceiling.
Let's see a closer view, July only, with the years marked on the graphs.
The early 1900's clearly dominates the record days. The three in the more recent times are not even close to being records at the top at 35C, 3C cooler than the record highs for the month at nearly 38C.
1911 is a prominent year of highs, comparing all the day's highs for 1911 throughout the summer with all the record years shows how each year can achieve the notoriety of being a record breaker.
The yellowed dots are 1911 placed on the previous graph of all record breaking day's temps. You can clearly see when each of the days gets into the range of the band of records are days of heat waves. As Homer would say, "DUH!" Three of these heat wave spikes are very well defined in the middle of May, beginning of July and part way through August.
One of the top summer record breaking year 1995, near today, looks like this:
One lucky quick warm front on the 14th of July 1995 managed to just poke into the lower range of the record days, and just happened to be the hottest day so far, and only because no other day has managed to get above that due to the shortness of the accounting.
2007 had three record breaking days, two in May and one in September. This is why:
A nice heat wave at the end of September pushed the temp near the ceiling. The summer, however, was obviously uneventfull.
Once this summer is over, I will plot 2010 on this same graph. Anyone want to bet with me that 2010 will be a "hotter" than ever year?