Worldwide storminess actually seems to have decreased slightly, rather than increased, as greenhouse gas levels have gone up. Hurricanes & tropical cyclones have no clear trend, and the frequency of severe (F3+) tornadoes is trending down:
The thumbnail image on the left was done the old-fashioned way: a thumbnail was made by editing the large image with an image editor, to scale and crop it appropriately:
<a href="…"> <img style="border:0" width=348 height=172 alt="" src="…"></a>
The thumbnail image on the right was scaled and cropped in CSS, like this:
<a href="…" style="display:inline-block;overflow:hidden"> <img width=348 height=191 alt="" style="border:0;position:relative;margin-bottom:-19px;top:-19px" src="…"></a>
As you can see, I chose to style the containing <a> tag, but you could style a <div>, instead.
The original image from NOAA is 960 × 720 pixels, but the top seventy pixels are a superfluous white border area. I needed a 348 × 172 thumbnail, without the extra border area at the top. The desired part of the original image is 720 - 70 = 650 pixels high. I needed to scale that down to 172 pixels, i.e., 172 / 650 = 26.5%. That meant 26.5% of 70 = 19 rows of pixels needed to be deleted from the top of the scaled image.
One artifact of this approach is that if you show the borders, the top border will be missing. Since I use border=0 anyhow, that wasn't an issue for me.
For other approaches to this problem see: