climateprediction.net (CPDN) applications are 32bit.
Some 64bit Linux distributions do not have 32bit compatibility libraries installed by default. In order to run cpdn on a 64bit Linux operating system without errors, you may have to install these 32bit compatibility libraries.
See this boinc wiki article for instructions on installing these compatibility libraries on certain versions of Fedora and Ubuntu.
Edit 1...The above link works for some versions of Ubuntu/Debian and Fedora. The 32 bit compatibility libraries may be named differently on later distributions of these operating systems. See this post for the differently named compatibility libraries for more recent versions of Ubuntu/Debian. Or this post for another way to do it in Debian.
Edit 2...you can run the command "ldd" from command line in a terminal window on the cpdn executable programs, which should give you the dependencies that need to be installed. The executables are in the projects/climateprediction.net directory under the main BOINC installation directory.
So, for each cpdn program/application in the ..../projects/climateprediction.net folder you would run an ldd command on it and it will return the needed dependencies.
ldd hadam3p_anz_um_6.10_i686-pc-linux-gnu (for a main model executable in for the regional Australia/New Zealand model)
ldd hadam3p_anz_graphics_6.10_i686-pc-linux-gnu (for the graphics display program for that model)
Of course the ldd command will only work if you are able to download the model executables in the first place (or if you move them over from another Linux PC where cpdn is working). So if the cpdn boinc site doesn't recognize your PC OS as compatible, you won't be able run the ldd command on anything since it won't download the files, unless you move over the BOINC folder from a Linux PC that works with cpdn, and then run ldd on the files in that transferred folder.