The main topic of conversation Monday was the Arctic air that filled the region. The high for the day failed to reach zero, making it the coldest day of the winter.

The last time the daytime high stayed below zero at the Minneapolis airport was Jan. 15, 2009. That's 1,467 days ago. I assume we have a similar record.

That's not the only string that we snapped this winter. Just before the new year, when the overnight low dipped down below zero, we also broke a string of about 350 days - nearly a full year - in which the temperature never fell below zero at any time during the day or night.

Now, the colder weather this winter may bring back memories of what it used to be like, but we are just getting short blasts of old-fashioned winter. Remember, we have had temperatures climb to nearly 50 a few times this January and the ground is mostly bare from the last thaw.

I remember when experiencing frequent subzero temperatures during the winter was normal and suffering through a string of days when the temperature never got above zero wasn't unusual.

It isn't just anecdotes and vague feelings that point to a change in the climate in Minnesota. A panel of scientists from the University of Minnesota recently made a presentation to three House committees in St. Paul showing that the climate in the state is behaving outside the historical realm that has been observed for the last 150 years, and frequent shifts in weather extremes are occurring at rates never observed before in the state's history.

Dr. Mark Seeley, an Extension climatologist, outlined a number of recent global trends by way of introduction - including doubling of the population and tripling of food consumption and water use - saying there has been more change in the last 50 years than all previous generations combined, according to Public Information Services of the Minnesota House of Representatives.

He also spoke about climate change, warning lawmakers that three attributes of climate are changing: temperature, water vapor and moisture. Longer growing seasons, changes in fisheries management and increased opportunities for invasive species are a few of the consequences of those changes.

Yet, all this evidence, whether it is our own observations or hard data provided by scientists, doesn't convince everyone that climate change is real and a real threat.

Let's hope it doesn't take conditions such as those in Australia, which is experiencing summer while we freeze, to convince them.

In Oodnadatta, an Outback town in South Australia, the roads melted. Sydney, Australia's biggest city, sweltered through heat of 108 degrees. In Tasmania a Dunkirk-style flotilla of small craft swung into operation to rescue locals and tourists stranded by fires on the isolated Tasman Peninsula.

Australia is getting ever hotter, according to the Economist magazine. The 2013 heat wave has set a new record for the highest national average temperature at 104.5 degrees.

The authorities are preparing for such temperatures as the new normal, reported the Economist. The Bureau of Meteorology added new colors, purple and pink, to its weather map to denote temperatures once considered off the scale: 122 to 125.6 degrees and 125.6 to 129.2 respectively. The bureau says that more "significant records" are likely to be set, with no end to the heat wave in sight.

Some climate experts are convinced that the 2013 heat wave will prove a turning point in how people in Australia, where climate-change skeptics often have swayed political debate, respond to warnings about human-induced climate change, concludes the report in the business magazine.

Although we never experienced 120-degree heat, Minnesota experienced at least 168 record-breaking extreme weather records in 2012, most of them related to heat. For example, 42 counties had record-breaking heat with a total of 90 new heat records. The state also had 36 large wildfires last year.

The nation experienced the hottest March on record in 2012 and July was the hottest single month ever recorded in the lower 48 states. As a whole, 2012 was the warmest year ever recorded in the United States, according to the National Oceanic and Atmospheric Administration's state of the climate report released earlier this month.

NOAA has also estimated that 2012 will surpass 2011 in total costs for U.S. annual billion-dollar disasters.

Some of the more significant ones include:

• The summer of 2012 was the worst drought in 50 years across the nation's midsection, with over 1,300 counties in 29 states declared drought disaster areas.

• Wildfires burned over 9.2 million acres in the United States and destroyed hundreds of homes. The average size of the fires set an all-time record of 165 acres per fire.

• Hurricane Sandy's storm surge height, 13.88 feet, broke the all-time record in New York Harbor, and destroyed communities across New Jersey and New York with floodwaters and winds. The cost of Sandy reached an estimated $79 billion with at least 131 deaths reported.

The evidence should be changing minds about climate change. But, even for those convinced, there is reluctance to make changes due to the costs, particularly in this fragile economy.

However, the evidence is piling up that inaction is costing us more as we pay out for damage from hurricanes where they have never been a problem before, wildfires that keep getting larger, drought that eats into our food supply or tornadoes that are becoming more frequent.

Climate change doesn't have a defining moment, such as Sandy Hook, that compels us to start a discussion on a solution. Still, it is one of the most important issues of our time.

We may be amused at some of the weather patterns that have become the new normal for historically frigid Minnesota, but a shifting climate, which includes the likelihood for extreme weather trends, can pose threats - to our agriculture, our economy and our health.