Geomatician from Orléans' University of Earth Science teach students to use software like ENVI (by Exelis). It is not difficult to use, and can be quite powerfull : vegetation growth rate, ice melting, depending on your subject. Determine ROI (region of interest) and it will enlight every point of your images that have the same caracteristics (on every wawelenght you have in satellite image, infrared or ultraviolet included).

Dear Thadee

How ENVI can be obtained? It is a commercial or free downloadable software?

http://www.exelisvis.com/ProductsServices/ENVIProducts.aspx

Here is a link to their website. It's probably a commercial licence.

Dear Mohamed Awad Dadamouny,

So far I know there is no software that have the facility to get ready knowledge about environmental change. To understand if there is any change of environmental issues you have to take time series satellite images (LANDSAT, TERRA or AQUA MODIS, NOAA-AVHRR)  of say 10, 20 or 30 years and have to analyze these images using image processing software -like ERDAS IMAGINE , ArcGIS or other same type of softwares. Many preprocessing steps have to follow depending on your final goal or interest. Many other measured data (meteorological) or data from different models are also necessary as input to finally get information about any change happened. If you search the net using "environmental change" as key word you will get plenty of papers on this issue.

Dear Mohamed Awad,

Just like some of the answers above, the software of interest and the methods or steps to go through depends much on the expected result/target. There are many commercially licensed as well as open source image processing softwares that you can deploy to achieve your result. You simply need to know 'which' software is good at 'what'. Meanwhile, you can try GRASS and ILWIS which I believe are open source applications. You will definitely need to know how to manipulate them to achieve your desired result.

All the best.

HI, it's really less of a software problem. As I see it, the way to approach this problem is the following:

- define what you mean by "environmental changes". It means very different things to different people.

- what's the spatial scale of the changes you are after?

- do you understand their dynamics and natural variability or normal changes throughout a year? [if you don't you risk "seeing" changes that are spurious, i.e. that are part of natural variability and not a real change)

- clearly define characteristics of your change

- which of those are expressed in remote imagery? How and specifically in which images (in terms of spatial resolution and spectral characteristics)

- once you understand the dynamics of your phenomena of interest and their variability, determine which imagery has suitable temporal characteristics?

Then, and only then, are you ready to look at the actual change detection part, which includes choice of software. But also here you first need to determine how your parameters of interest can be extracted from the images you identified as useful (this could be simple methods that are implemented in any remote sensing software, but it could also be more specialized procedures that requires more specialized tools).

Hope this helps,

Norman

In addition to the above answers to your question, you'd better to know "environmental change" is a holistic term and includes the change of different environmental elements. Hence, "environmental change" can be broken down into "change of several or a number of environmental elements" which are represented by different land use/land cover (such as urban extension, cropland conversion, water body change, forest cover change, biomass or sequestrated carbon change and so on). You can also focus your change detection on certain aspect, e.g., snow cover, forest, fire/burning, water body, irrigated and non-irrigated cropland, woodland, etc. In fact, the change of all these indicators may be highlighted by greenness (e.g., NDVI, Tasseled Cap Greenness, and other different vegetation indices), soil brightness (Tassled Cap Brightness, albedo) and soil moisture (e.g., Tasseled Cap Wetness, NDII and so on) during certain time interval/span. Biomass change detection needs specific approaches to estimate single biome or multi-biome level biomass, and then to track its change over time. 

Regarding the change detection technique, you may find hundreds of publications about it. I have some publications related to this topic and may give you some idea. You can find them on my profile.